Difference between revisions of "Pachypodium brevicaule"

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{{Taxobox
 
{{Taxobox
 
| color = lightgreen
 
| color = lightgreen
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| name = ''Pachypodium''
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| name = ''Pachypodium brevicaule''
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| image = Pachypodium_lamerei.PNG
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| image = Pachypodium brevicaule 1.jpg
 
| image_width = 250px
 
| image_width = 250px
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| image_caption = The pachycaule trunk of ''[[Pachypodium lamerei]]''
 
 
| regnum = [[Plantae]]
 
| regnum = [[Plantae]]
 
| divisio = [[Flowering plant|Magnoliophyta]]
 
| divisio = [[Flowering plant|Magnoliophyta]]
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| ordo = [[Gentianales]]
 
| ordo = [[Gentianales]]
 
| familia = [[Apocynaceae]]
 
| familia = [[Apocynaceae]]
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| genus = '''''Pachypodium'''''
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| genus = ''[[Pachypodium]]''
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| genus_authority = [[John Lindley|Lindl.]]
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| species = '''''P. brevicaule'''''
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| subdivision_ranks = Species
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| binomial = ''Pachypodium brevicaule''
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| subdivision =
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| binomial_authority = Baker
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''[[Pachypodium ambongense]]''<br />
 
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''[[Pachypodium baronii]]''<br />
 
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''[[Pachypodium bicolor]]''<br />
 
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''[[Pachypodium bispinosum]]''<br />
 
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''[[Pachypodium brevicaule]]''<br />
 
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''[[Pachypodium cactipes]]''<br />
 
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''[[Pachypodium decaryi]]''<br />
 
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''[[Pachypodium densiflorum]]''<br />
 
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''[[Pachypodium eburneum]]''<br />
 
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''[[Pachypodium geayi]]''<br />
 
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''[[Pachypodium gracilius]]''<br />
 
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''[[Pachypodium horombense]]''<br />
 
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''[[Pachypodium inopinatum]]''<br />
 
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''[[Pachypodium lamerei]]''<br />
 
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''[[Pachypodium lealii]]''<br />
 
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''[[Pachypodium makayense]]''<br />
 
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''[[Pachypodium meridionale]]''<br />
 
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''[[Pachypodium menabeum]]''<br />
 
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''[[Pachypodium namaquanum]]''<br />
 
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''[[Pachypodium rosulatum]]''<br />
 
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''[[Pachypodium rutenbergianum]]''<br />
 
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''[[Pachypodium saundersii]]''<br />
 
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''[[Pachypodium sofiense]]''<br />
 
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''[[Pachypodium succulentum]]''<br />
 
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''[[Pachypodium windsorii]]''
 
 
}}
 
}}
  
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'''''Pachypodium''''' is a [[plant]] [[genus]] that belongs to the dogbane [[family (biology)|family]], [[Apocynaceae]].  ''Pachypodium'' comes from [[Greek language|Greek]] ''pachy'' (thick) and ''podium'' (foot), hence meaning ''thick-footed''.
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'''''Pachypodium brevicaule''''' is a species of plant that belongs to the dogbane family [[Apocynaceae]], which is now amplified by the inclusion of the milkweed family [[Asclepiadaceae]] -- ''an important union to botanists and horticulturalists interested in the alliance [[succulent]]s''.
  
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==Genus characteristics==
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===[[range (biology)|Distribution]]===
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This plant is native to [[Madagascar]], from the south of Antananarivo to the Itremo Mountains.
  
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All ''Pachypodium'' are [[succulent]] plants that exhibit, to varying degrees, the morphological [[characteristic]]s of pachycaule [[trunk]]s and [[spinescence]]. These are the most general features of the [[genus]] and can be considered distinguishing characteristics.
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===Habit===
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A flattened, tuberous, [[cactus]]-like plant with a very low [[trunk]] and a very wide, exaggerated diameter without substantive branching whatsoever with exception to several extremely short flattened "branch"-like [[nodes]] or [[rosettes]] of [[leaf|leaves]].
  
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The pachycaule trunk is a morphologically enlarged trunk that stores water so as to survive seasonal [[drought]] or intemitent periods of root desiccation in exposed, dry, and rocky conditions. Whereas there is great variation in the habit of the plant body, all ''Pachypodium'' exhibit pachycaul growth. Variation in habit can range from dwarf flattened plants to bottle shaped shrubs to dendroid-shaped trees.
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===[[Ecology]]===
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''Pachypodium brevicaule'' Baker grows in open, [[deciduous]] Western [[forest]] of Madagascar in full sun on [[sandstone]], rarely on [[granite]], in [[crevices]] between outcrops of [[quartzite]]. With a [[pH|pH. Level]] varying from 3.5 to 4.5, it is strictly adapted to growing in [[acid]] [[Substrate (biology)|substrate]]s. (That strictness to acidity seemingly has implications to its [[cultivation]].) It is found in the [[evergreen]] [[Sclerophyllous]] (''[[Uapaca]]'') [[woodland]] or [[savanna]] zones dominated by scattered [[woody]] plants. It grows at [[altitude]]s of 1250-1900 (2000 m) m.
  
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The second general characteristic of ''Pachypodium'' is spinescence, or having spines. The spines come clustered in either pairs or triplets with these clusters often arranged in rings or whorls around the trunk. Spines emerge with leaves, and like leaves grow for a short period before stopping growth and hardending. Spines do not regenerate so weathering and abrasion can wear away all but the youngest spines from older specimens - leaving smooth trunks and branches.
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Associated plant [[species]], site indicators, include ''[[Pachypodium densiflorum]]'', ''[[Pachypodium eburneum|P. eburneum]]'' ([[Apocynaceae]]), ''[[Aloe]] compressa,'' ''A. capitata,'' ([[Asphodelaceae]]), ''[[Euphorbia]] quartzicola'' ([[Euphorbiaceae]]), ([[Orchidaceae]]), ([[Graminaea]]), ([[Moss|Bryophyta]]), and [[Lichen]]es.
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It occurs in a region that receives an annual [[rainfall]] of 1354 mm with a number of [[drought|5 dry months]]. Average monthly [[temperature]]s varies from 9°C to 17°C. The yearly average temperature is higher; however, at 13°C to 18.4°C.
  
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To some extent, [[branch]]es are a characteristic of the genus.  Some caution is warranted in over-generalizing this characteristic. ''[[Pachypodium namaquanum]]'' is often branchless. ''[[Pachypodium brevicaule]]'' has no clear branches, and indeed may have evolved an alternative to branching in the form of nodes from which leaves, spines, and [[inflorescence]]s emerge. In general ''Pachypodium'' have few [[branch]]es. Since the environmental stresses and factors that contribute to branching can vary widely even in small areas, individual plants of the same species exhibit wide variation in branching morphology.
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===[[Vernacular]] [[Malagasy]] Common Name===
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"Tsimondrimondry" ([[Merina]]); "Kimondromondro" ([[Betsileo]])
  
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Unlike many members of the [[Apocynaceae]], including some members of the superficially similar ''Adenium'', ''Pachypodium'' species do not exude a milky [[latex]]. Rather, the [[sap]] is always clear.  
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==[[Morphology (biology)|Morphology]]==
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===Habit===
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''Pachypodium brevicaule'' is unique to the [[genus]] in habit. It is considered a [[dwarf]] plant. It takes on a broad flattenened tuberous, cactus-like habit that has a very short [[trunk]] measuring 2 to 8 cm high and an exaggerated diameter that can reach 10 to 40 cm. When in [[flower]] the plant gains stature by reaching a height of 25 cm. ''Pachypodium brevicaule'' Baker barely, if all, "branches." Rather it seems to form protruding [[nodes]] or [[rosettes]] of leaves that ranch from 1 to 4 cm in length and 2 to 4 cm in width. In the "Botanical Key for the Genus ''Pachypodium''," the character "without branches or branchlets" is a distinguishing [[Morphology (biology)|morphological]] character to the species ''Pachypodium brevicaule'''s definition.
  
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===Morphology===
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The [[bark]] is colored pale grey and is sometimes shiny. It has a smooth texture. The bark is about 2 to 4 mm thick, with the [[wood]] being greenish. The "branches" or, better said, nodes of rosettes of leaves, when fresh, have paired, rather soft, curved [[spine (biology)|spine]]s at their [[apex|apices]], measuring 2 to 9 mm long by 1 to 1.5 mm at the base. They are pale grey to pale brown. When young, they are [[pubescent]] and more or less flat.
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:''For detailed description of the morphology of the genus, see [[Morphology of Pachypodium]].''
 
  
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The [[Morphology (biology)|morphology]] of the [[genus]] ''Pachypodium'' varies significantly both within and between species and is highly responsive to its immediate surrounding [[microenvironment]].   ''Pachypodium'' do not overly respond morphologically to larger vegetative zones. For example, ''Pachypodium'' can sometimes occur in prehumid vegetative zones where a taxon might find a suitable habitat on a rocky, sunny [[inselberg]] jutting above the humid canopy of the forest.
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===[[Leaves]]===
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''Pachypodium brevicaule'' has leaves that are confined to the apices of the branches or nodes and rosettes. The leaves are [[sessile]], without a [[Plant stem|stem]], [[Petiole (botany)|petiolate]]--''with a [[stalk (botany)|stalk]]''--[[peduncle]]--''the main axis of the [[inflorescence]]''--or [[pedicel]]--''the stalk of a single flower''--or it is shortly petiolate--''having a stalk.'' If it has a stalk, the [[Petiole (botany)|petiole]] measures up to 2 mm long. It is sparsely pubescent, fuzzy.
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The leaf blade is [[herbaceous]], not woody-like, and [[glaucous]], covered in a very fine [[bloom]] or a fine powdery layer, when fresh and papery when dried. The blade is shaped [[ovate]], broad and rounded at the base and tapering toward the end, to [[obovate]], egg-shaped and flat with the narrow end attached to the stalk. It measures 11 to 30 mm in length by 6 to 12 mm in width. The apex of the blade is [[acuminate]], narrowing to a slender point. The base is blunt or rounded. The blade of ''Pachypodium brevicaule'' Baker is [[glabrous]], smooth, to sparsely pubescent, slightly hairy, on both sides, with impressed [[venation]] above, and with midrib and secondary veins prominent beneath. There are 15-30 pairs of secondary veins, which are straight at the base, upcurved at the apex, and forming an angle of 45-85° with the costa, or the midrib of a leaf. The [[tertiary]], third-level, venation are [[reticulate]], forming a web or a network like pattern.
  
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Morpholigically, ''Pachypodium'' can be highly ''flexible'' in organization. Branching, if present at all, can be from either the base of the plant or at the crown. Freeform branching is a morphological adaptation to factors of the immediate microenvironment which, by their diversity, account for the wide range of habits:
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===[[Inflorescence]]===
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The inflorescence of ''Pachypodium brevicaule'' is [[sessile]], with a stalk, or [[pedunculate]], with the main axial stem to an inflorescence. It can be congested with up to 7 flowers where the inflorescence measures 2.5 to 15 cm in length by 2 to 6.5 cm in width. The peduncle, itself, is glaucous and covered in a fine bloom. It takes the shape of a [[terete]], an elongated cylindrical form that is round in cross-section. The terete measures roughly up to 120 mm in length by 2 to 4 mm in width. The degree of pubescent varies on the peduncle from sparsely to fully hairy, pubescent. The pedicels, the stalk of a single flower, measures up to 8 mm long and is hairy, pubescent.
  
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* flattened dwarf species less than 8 cm tall but reaching 40cm in diameter
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The [[bract]]s, modified leaves at the base of a pedicel of a flower, a peduncle, or a branch, are longer than the pedicels on ''Pachypodium brevicaule'' Baker. They are narrowly oblong, having a somewhat elongated form with approximately parallel sides, to obovate, egg-shaped and flat with the narrow end attached to the stalk. The bracts measure from 5 to 13 mm long by 1.5 to 3 mm wide.. At their apex, they are [[acuminate]], tapering gradually to a sharp point, or [[Angle#Types_of_angles|acute]], having a sharp point or tip. On the outside, the bracts are fully pubescent, hairy to slightly so. Inside they are less so.
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* bottle- or oval-shaped shrubs to 4 m tall
 
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* both branching and unbranched cigar- and cactus-like trees to 5m tall.  
 
  
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Despite microenvironmental variation, ''Pachypodium'' are always succulent and always exhibit pachycaul trunks. ''Pachypodium'' are usually spinescent, but individual variation in spinescence as well as weathering/abrasion can result is plants with few if any spines.
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=====[[Flower]]s=====
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The sepals of ''Pachypodium brevicaule's'' flower are glaucous, having a fine bloom over the surface. This bloom covers the [[anatomical terms of location|basal]] part of the [[corolla tube]], the [[petals]] of a flower considered as a group or unit and usually of a color other than green, or the inner whorl of the [[perianth]] shaped like a tube. The sepals are [[connate]], united to a structure of the same kind, i.e. other sepals, at the base for about 0.5 mm. They are narrowly ovate, broad and rounded at the base and tapering toward the end, or narrowly oblong, having a somewhat narrowly elongated form with approximately parallel sides. The sepals measure 6 to 11 mm long by 2 to 3 mm wide. At the apex, they are acuminate, tapering gradually to a sharp point, or acute, having a sharp point or tip. Outside the sepals are often glabrous and smooth; whereas inside in the lower part and near the apex, they are slightly pubescent, hairy.  
  
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===Adaptive Features===
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=====[[Corolla]]=====
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The corolla, the inner whorl of the perianth, is bright yellow. It measures 17 to 25 mm long in the mature [[bud]] and forms a comparatively wide broadly [[ovoid]], shaped like an egg, ovate, head measuring 7 to 11 mm long by 5 to 8 mm wide. The apex of the bud is [[obtuse]], having a blunt or rounded tip. Overall the bud is pubescent outside. The [[corolla lobes]] are not as hairy; however. Especially where the lobes and tubes are covered in bud, the surface is glabrous. The pubescent belt inside the corolla tube is 2 mm above to 1 mm below where the [[stamens]] are inserted, not emerging beyond the corolla tube. Otherwise the corolla tube is glabrous and smooth. It is shaped like a funnel, [[infundibuliform]], at 12 to 18 mm long (1.63 times as large as the calyx and 1.05 to 1.36 times as long as the lopes) The basal of the corolla tube is almost cylindrical. It is 2 to 3 mm long by 2 to 2.5 mm wide above the base (0.15 to 0.18 times the entire length of the entire tube.) The upper part of the corolla tube is almost cylindrical. Yet it widens at the throat altering the cylindrical form. The upper part measures 10 to 15 mm long by 5 to 5.7 mm wide at the mouth. The lobes are obliquely obovate, having sides of unequal length or form, which are egg-shaped and flat with the narrow end attached to the [[stalk (botany)|stalk]]. At their apex, the lobe of ''Pachypodium brevicaule'' Baker are rounded. They measure 9 to 18 mm in length by 8.5 to 14 mm in width. (That is, in proportion, the lobes are 0.73 to 0.94 times as long as the corolla tube and 1.1 to 1.3 times as long as they are wide.)
  
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Variation among ''Pachypodium'' species is significant but all ''Pachypodium'' are succulent plants inhabiting seasonally or chronically dry landscapes. The genus employs two morphological [[adaptations]] to these [[xeric]], isolated, habitats: Pachycaul trunks and spinescence.
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=====Stamens=====
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The stamens of ''Pachypodium brevicaule'', with an apex of 4 to 9 mm below the [[mouth]] of the corolla tube, are inserted, meaning they do not extent beyond the corolla tube or mouth of the flower. They measure from the base 3.5 to 4 mm. (Proportionally they are 0.22-0.29 of the length of the corolla tube.) The stamens are the "male reproductive" organ of an angiospermous flowering plant.  
  
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====Pachycaul Trunks====
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The anthers, the part of the stamen, typically on top, which bears the pollen, commonly consisting of (1) two of four [[theca]]e, which contain the [[pollen]] and (2) a [[infertility|sterile]] region in between the connective that is very narrowly triangular. The anthers range in size for ''Pachypodium brevicaule'' from 4.7 to 5.2 mm long by 0.7 to 0.9 mm wide. (Proportionally, that is, they are 5.22 to 7.14 times as long as wide.) Inside, the anthers are pubescent and hairy at the base of the connective, the part of tissue in a stamen that separates the two thecae of an anther. As well, it is pubescent just below where stamens cohere with the [[pistil head]], the fertile region of the flower.
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''Pachypodium'' trunks and branches are anormally thickened with water-storing tissue. Plants must relie on the food and water stored in their thickened trunks during seasonal or intermittent drought when leaves have been shed and no water is available from the substrate. In addition to the lower surface-to-volume ratio which aides in water retention, the thickened trunks and branches can also possess photosyntehtic surface tissue to allow nutrient synthesis even when leaves are not present.
 
  
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Some species of pachypodium have developed geophytic pachycaul trunks, or trunks that are beneath the [[soil]]'s surface. These geophytic trunks are caudexes, enlarged stems or trunks that store water. They should not be mistaken for [[root|roots]], because the enlargement occurs above the point where the roots branch off the main axis of the [[trunk]].
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=====[[Pistil]]=====
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Composing the female reproductive organ, the [[pistil]] varies in length from 4.8 to 6.5 mm.  
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Pubescent and hairy, the [[ovary (plants)|ovary]] measures ovary 1.5 to 1.9 mm long (x) by 1.3 to 1.6 mm wide (y) by 1.2 mm high (z). The [[disk]] in a pistil is the slightly thickened, or otherwise distinguished region, around the [[carpel|style]] in certain flowers that secret [[nectar]]. The disks of ''Pachypodium brevicaule'' Baker number 5 broad ovate glands that are broad and rounded at the base and tapering toward their end. These glands, for which either 2 or 2 pair can be partly fused together, are about half as long as the ovary. (Proportionally that 0.5 times 1.5 to 1.9 mm.).
  
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====Spinescence====
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The often cylindrical stalk-like portion connecting the [[carpel|stigma]] with the [[carpel]] or ovary, the style is slightly pubescent and hairy at the base for the [[taxon]]. The stigma is the top-most receptive region of the style, which often divided into [[stigma-lobes]] that are commonly wet by a sticky exudate that helps captures and nourish pollen grains. The carpel, furthermore, is the female organ of the angiospermous flower that consists of a modified leaf that contains the ovules. Several carpels can be fused together to from a compound ovary.
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''Pachypodium'' make use of [[spinescence]] as an adaptive mechanism responding to the landscape. Adaptively this spinescence is employed to different degree in various species to collect [[moisture]] from [[fog]]s and [[dew]]s. The spines point in all angles, are paired or in sets of threes where the third spine is unequal, and thus captures moisture that can drip directly down to the [[soil]] beneath the plant from the branches and branchlets. The degree of spinescence demonstrates the degree to which species rely on spines as a means to collect [[moisture]] from [[microclimate]] conditions, such as localized [[dew]]s or [[fog]]s within microenvironments, and drip to the [[soil]] immediately below the spine on a branch or branchlet.  The falling [[moisture]] immediately around the plant saturates the soil. A superficial root system will often develop to take advantage of this source of moisture.
 
  
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The concept of "[[micro]]-[[endemic (ecology)|endemism]]" plays an important role in this relationship between adaptation mechanisms and speciation.  It suggests a certain small scale "nativeness" by virtue of originating or occurring naturally in a particular [[place]] or [[location (geography)|location]].  The [[landscape]] of Madagascar is a perfect example of "micro-endemism" for species of ''Pachypodium'' and other taxa. Three factors can be seen to attribute speciation, or the occurrence of species diversity, via adaptive mechanisms to accelerated [[evolution]] as it occurs within the xeric landscape and [[climate]].
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The slightly pubescent style for ''Pachypodium brevicaule'' measures 2.6 to 3.6 mm long. The pistil head, the separate part attached to the style, is 0.71 to 1.0 mm high. It composition is complex. Its basal part is 0.4 to 0.6 mm long by 0.4 to 0.6 mm wide. The central part is ring-shaped at 0.15 to 0.2 mm in length by 0.5 by 0.7 mm in width. And, its [[stigmoid]] apex measures 0.1 to 0.15 mm long by 0.3 to 0.5 mm wide.
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Each [[carpel]] contains approximately 50 ovules.
  
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(1) The variation of geology and topology in dry climates is thought to have a greater effect upon plants than in areas with high rainfall. Xeric environments are thus more demanding of adaptive mechanisms to aid in the plant's survival than in places where rainfall is plentiful. The more the demanding, generally the more "mechanized" or "mechanisms" are needed to aid the plants' survival.
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====[[Fruit]]====
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The fruit of ''Pachypodium brevicaule'' has two separate [[mericarps]] that form an angle of 5-45° at its base. Sometimes it is possible to see flowers on the same inflorescence that has fruit. Mericarps are the parts of a "[[schizocarp]]" fruit, that becomes dry at maturity and subsequently splits or breaks into several smaller pieces--''i.e. individual mericarp or seed. The mericarps are colored pale to dark brown with longitudinal lines outside and whitish inside when dried. The fruits are [[fusiform]] at 57 to 140 mm long (x) by 3 to 5 mm wide (y) by 2 to 4 mm high (z). They are obtuse, having a blunt or rounded tip, to acute, having a sharp point or tip, at the apex. The surface of the fruit is pubescent and hairy. The exterior wall is 1 mm thick.
  
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(2) The geological formations of locally xeric landscapes break up [[populations]] of [[organism]]s, i.e. [[plants]], into smaller groups, where each group can initially interbreed but, with time, develop new [[genotypes]] and cannot be bred with exception to natural [[hybrid]]ization.  Localized [[geology]] becomes harder to cross over for a given population to be "continuous" in a xeric geological landscape, because more demands are placed on the population. Therefore, populations are broken down into smaller units within this landscape. Groups of the original population become located to unique [[microenvironment]]s within the landscape. Accordingly measures to adapt to these microenvironments become more singular to the isolated habitat. Adaptive mechanisms are employed so as to aid the survival of the plant group. This adaptation eventually, in part, leads to speciation in the habitat, or diverse species across the spectrum of the landscape.
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=====[[Seed]]s=====
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The seed of ''Pachypodium brevicaule'' Baker is pale brown. It is shaped in an [[elliptical]] manner. Its margin has a distinct broader that is [[revolute]], rolled backward from the tip or margins to the undersurface, towards the [[hilar]]. The hilar pertains the [[hilum]], which is a scar on a seed indicating the point of attachment to the [[funiculus]], the stalk connecting a seed with the placenta. The seed measures 3.5 to 3.9 mm in length by 1.5 to 1.8 mm in width. The [[testa]], the outer and normally hard and protective layer of the seed, is smooth. The coma of ''Pachypodium brevicaule'' Baker is straw-colored at 13 to 21 mm long. A coma is usually terminal tuft of hairs on a seed. In the case of ''Pachypodium'', the coma allows the seed to be airborne, as that is its means of distribution.
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Whereas the [[embryo]] measures 3.2 to 3.5 mm in length, the [[cotyledons]] are 1.5 in length by 1.5 mm in width. The cotyledons are ovate in shape, meaning that they are broad and rounded at the base and tapering toward the apex. They are cordate, having a heart shape, at the base. The rootlet is 2 to 2.5 mm long by 1.2 mm wide. (Proportionately that is 1.3 to 1.6 times as long as cotyledons)
  
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(3) Taxa tend to develop specialized xeromorphoric structures at some architectural level in [[arid]], geological and [[topology|topological]] landscapes, where a strategy of a "flexible" and "strict" architectural, organizational morphology at various levels of structure for ''Pachypodium'' becomes advantageous to succeeding in the isolated, specialized landscape. This strategy is seen in the manifest ''flexible'' variations of habit in species of ''Pachypodium'' while all the same they are "strictly" xeromorphic pachycaule trunks meant to conserve water for dry periods. At another level of structure, namely that of organs, we can see that [[dew]] and [[fog]] dripping spines are examples of a xeromorphic adaptive mechanized organ responding to microenvironments.
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===Literature===
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''Pachypodium brevicaule'' Baker
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John Gilbert Baker published ''Pachypodium brevicaule'' in 1887 in Journ. Linn. Soc. Bot. 22: 503 (1887).
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In 1934, J. M. H. A. Perrier de la Bâthie published an account of the taxon in Bulletin de la Société Botanique de France. 81: 303 (1934).
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Pichon, in 1949, offers another account of ''Pachypodium brevicaule'' Baker in Mém. Inst. Sc. Madag. sér. B, 2: 122 (1949).
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The latest account, before ''Rapanarivo et al'' is provided by Friedrich Markgraf within, Fl. Madag. fam. 169: 299 (1976).
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The [[holotype|Species Type]] is: '''Madagascar, sin. loc., Baron 4412 ([[holotype]] The Herbarium of the Royal Botanical Garden at [[Kew]], near [[London]]; [[isotype]] The Herbarium of the Laboratoire de Phanérogamis at [[Paris]]). Fig. 3, p. 18; Map 2, p. 12; Plates 8-10, opposite p. 17.'''
  
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These newly created species from within the xeromorphic landscape take on different characters as responses to the [[habitat (ecology)|habitat]]. For instance, there is an advantage to morphologically developing into bottle-shaped "shrubs" where the plants exist in open, sunny microenvironments on top of porous [[sandstone]].  Little completion exists for height within the habitat.  Likewise, where competition for resources is more competitive--''both in the number of species and the height of surrounding plants''--there are times when it is to the advantage of a plant to develop into arborescent, dendroid “trees.” This development is because these particular ''Pachypodium'' must compete with other plants for resources in a dry deciduous forest, composed of, perhaps, arborescent ''[[Aloe]]'', members of the [[Didiereaceae]] genera''--[[Alluaudia]], Alluaudiopsis, Decaryia, and Didierea; all endemic to Madagascar--''and ''Uncarina'' species, for instance.
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===External sources===
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The adaptive mechanism in a morphological form and an ecological response to habitats are typically manifested together at once for the genus ''Pachypodium.''
 
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Examining ''Pachypodium'' reveals characteristics of various organs that adapt to the microenvironment. These adaptations, variations on habit, [[trunks]], [[branches]], branchlets, [[spine (biology)|spine]]s, [[leaves]], or [[flowers]], are plentiful in demonstrating how ''Pachypodium'' as a genus fosters greater variation in its speciation. The manner in which speciation occurs in ''Pachypodium'', therefore, is apparent: adaptive mechanisms on a morphological level respond to the microenvironment of ''Pachypodium'' habitat. The genus' unique organizational, architectural morphology shapes plants that are highly, adaptively responsive to their immediate, surrounding, microenvironments. The duplicity of an adaptive mechanism that is at once "strict" and "flexible" at differing levels of plant physiology, or structure, has granted ''Pachypodium'' the ability to evolve within the landscape into variations that fulfill an [[ecology|ecological]] niche as various species.
 
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The [[hypothesis]] of micro-endemism, therefore, states that speciation occurs in small specific habitats as aided by adaptive mechanism occurring in geological, topographical, and climatic isolation. Geologically and topographically, plant populations in xeric climates are broken down into smaller groups. The microclimate responds to the given location transforming it into a habitat.  Isolated , the duplicity of organization in ''Pachypodium'' form through geology and location significant variation where over evolutionary time a new species might develop, if not have developed. The development of new species is through, in part, the adaptive mechanisms of pachycaule and spinescence as well as strict and flexible structural organization at various levels of plant physiology.
 
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==Taxonomy==
 
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:''See main article [[Taxonomy of the Pachypodium genus]].''
 
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===Number of species===
 
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There are now 25 known species, of which 20 come from [[Madagascar]], where isolated [[landscape]]s and [[micro]]-environmental conditions have produced highly [[specialized]] species. The species count continues to grow as ''[[Pachypodium menabeum]]'' has been resurrected from invalid taxonomy and ''[[Pachypodium makayense]]'' added newly to the list. One can speculate that in regions such as [[Madagascar]], there might still be unidentified species that are confined to a single rocky outcrop or an [[inselberg]].
 
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===Affinities within the Apocynaceae===
 
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The family Apocynaceae before it included Asclepiadaceae had 3 [[genus|genera]] that can be considered [[succulent]] [[plant]]s: ''Adenium'', ''Pachypodium'', and ''[[Plumeria]]''. The first two genera (''Pachypodium'' and ''Adenium'') are generally assumed to have closed association with each other.  Studies; however, of these two genera reveal that they are not as intimately close as once thought.
 
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However, a study of key characteristics of the taxon and a [[cladistic]] study of the [[subfamily]] Apocynoideae and the family [[Asclepiadaceae]] (before its merging with the [[Apocynaceae]]), demonstrates that this closed association is not warranted. True, both are succulent plants and pachycaule. According to Leeuwenberg however, ''Adenium'' is maintained in the subtribe Neriinae, placed underneath the [[tribe]] Wrightieae whereas ''Pachypodium'' is placed beside the in the subtribe Pachypodiinae, within the tribe Echiteae.  Though related, these taxa means that the two are not intimately related.
 
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==Distribution and habitats==
 
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===Distribution===
 
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''Pachypodium'' are native to [[Madagascar]] and continental [[Southern Africa]], i.e. [[Angola]], [[Botswana]], [[Mozambique]], [[Namibia]], [[South Africa]], [[Swaziland]] and [[Zimbabwe]].
 
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===Habitat===
 
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:''See main article [[Pachypodium habitats]].''
 
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In elevation, ''Pachypodium'' in both mainland [[Africa]] and [[Madagascar]] grow between an altitude of sea level, where some [[species]] grow in [[sand dunes]], such as ''[[Pachypodium geayi]]'', to 1600 m (5200 feet) for ''[[Pachypodium lealii]]'' in southern Africa and 1900 m (6200 feet) for ''[[Pachypodium brevicaule]]'' in Madagascar.
 
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In continental southern Africa, the extreme [[temperature]]s range from -10 °C (14 °F) in some locations to as much as 45 °C (113 °F). Whereas in Madagascar, with not such a great temperature amplitude, the temperature ranges from -6 °C (21 °F) to 40 °C (104 °F).
 
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A generalization about [[Precipitation (meteorology)|precipitation]] regimes for both southern Africa and Madagascar does not have much meaning because the habitats of ''Pachypodium'' vary so greatly with a moisture regime. In some places, ''Pachypodium'' receive annually from as little as 75 mm (2.95 inches) from the southern part of Africa to a high level of 1985 mm (78.15 inches). A precipitation regime for a species of ''Pachypodium'', therefore, depends upon a habitat's location relative to the influences of the [[Atlantic Ocean|Atlantic]] and [[Indian Ocean|Indian]] Oceans and the various mountain ranges of southern continental Africa and of Madagascar.
 
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The genus grows in areas where there are significant periods of [[dry season|dry months]] that range from five months to ten months. It would seem likely that the Atlantic and India Oceans pay a major role in the creation of weather conducive to [[rainfall]], not to mention [[mountain]] [[range]]s. For example, the [[Madagascar dry deciduous forests]] with their long dry season and severe limestone ridden soils provide one ideal setting for ''pachypodium''.
 
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''Pachypodium'' grows in various types of [[Substrate (biology)|substrate]]s. Some species only grow in one substrate whereas other will grow in several. The degree to which a taxon can grow in a given substrate seems to determine how specialized its [[habitat (ecology)|habitat]] is within the [[landscape]] and [[climate]]s. On outcrops, steep hills, and inselbergs, the plants are subjected to fluctuating [[moisture]], high [[wind]]s, and [[temperature]] extremes.  Only plants with special adaptations to exposure and extreme drought can survive, let alone thrive, on these exposed geological habitats. ''Pachypodium'' root in cleft, [[fissures]], and crevices of those rocky formations. The non-succulent roots penetrate deeply into the acuminated [[soil]], [[mineral]], and [[humus]] in these crevices. Moisture is able to seep deep into these crevices. Very little [[transpiration]] occurs.  In this manner, rocky substrates provide moisture in the habitat. This saturation of crevices can only occur, however, if there is not a considerable runoff from the rock's surface and if there is abundant fine soil in the cracks that, in turn, retain water. The [[Substrate (biology)|substrate]], therefore,  plays a critical role in the creation of micro-environmental "arid islands."
 
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Sand readily store water because it is taken up easily and there is less evaporation except for the top layer.  Very deep sand; however, has the problem of seepage. Yet in moderation shallow and deep sand substrates have water available to ''Pachypodium''.  With shallow sand substrates, ''Pachypodium'' grow on sand dunes near the sea.  Where water is in deep sandy substrate, ''Pachypodium'' grow on sand "over" [[laterite]] red soil.  Laterite soil is a largely impermeable soil that traps water for the use of the flora that include ''Pachypodium''.
 
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==Protection status==
 
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Internationally ''Pachypodium'' are protected under the [[CITES]] treaty. According to it, members of this genus cannot be collected from endemic, native locations within the landscape. They are not easily, readily  imported and exported between nations either. The protection afforded by the CITES treaty responses to two issues:
 
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*The esteem the genus has within Collector's and Nursery Trade. As highly esteemed plants, succulent enthusiast desire to collect more and more species and [[cultivar]]s. In the case of ''Pachypodium'', [[seed]], seedlings, and even mature, nursery-grown specimen plants are fortunately available readily in Nursery Trade.
 
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*Destruction of the genus's endemic [[habitat (ecology)|habitats]], e.g. through [[agriculture]].
 
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[[Extinction]] of identified species seems yet unlikely, as the collection of seed and the cultivation of the plant safeguard the genus.
 
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==History of the genus==
 
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:''See main article [[History of the genus Pachypodium]]''
 
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The early history of the [[genus]] ''Pachypodium'' demonstrates the typical process of a taxon becoming a new genus. Initially debate occurred over if ''Pachypodium'' belonged to the genus ''[[Echites]]'' or if it constituted a separate genus. ''Pachypodium ''were first published as a unique genus, separate from ''Echites'', by [[Leandley]] in [[1830]].
 
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Then the debate centered on the [[Botanical nomenclature|nomenclature]] of [[species]] uniquely found in continental [[Southern Africa]]. That changed when, in [[1892]], [[Baker (disambiguation)|Baker]] contributed the first species accepted into the genus from [[Madagascar]]. The degree of [[speciation]] then turned to [[Madagascar]], where the count of species far exceeds those on the mainland.
 
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In [[1907]], [[Costantin]] and [[Bois]] constructed the first [[monograph]], of ''Pachypodium'', in which they enumerated 17 species, where ten were from [[Madagascar]] and seven were from continental southern Africa.
 
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==Natural history==
 
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There is no [[fossil]] records of ''Pachypodium'' known. Yet certain conclusions can be drawn from the geology of the landscape in Madagascar as to the past [[natural history]] of ''Pachypodium''.
 
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==References==
 
 
*Eggli, Urs. (1993) <u>Glossary of botanical terms with special reference to Succulent Plants</u>. with German Equivalents (British Cactus & Succulent Society: United Kingdom)
 
*Eggli, Urs. (1993) <u>Glossary of botanical terms with special reference to Succulent Plants</u>. with German Equivalents (British Cactus & Succulent Society: United Kingdom)
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*Endress & Bruyns : "A revised classification of the Apocynaceae." ''Botanical Review'' '''66''': 1-56.
 
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*Endress, Mary: "The unification of Asclepiadaceae and Apocynaceae." ''Haseltonia: The Cactus and Succulent Society of America's Yearbook'' Vol. '''8'''.
 
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*Lavranos, John, J. "Pachypodium makayense: A New Species From Madagascar". ''Cactus and Succulent Journal'': United States '''76 (2)''' 85-88.
 
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*Lüthy, Jonas M. "Another look at the pachypodiums of Madagascar." <u>Bradleya: The British Cactus and Succulent Society Yearbook</u>. (22/2004) ISBN 0-902099-74-4
 
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*Mays, Harry. [European Union Honorary Representative] "The Huntington Botanical Gardens' 2005 offering of International Succulent Introductions for the European Union." [A Posting] (Woodsleigh, Moss Lane, St. Michaels on Wyre, Preston, PR3 0TY, UK: 2005)
 
 
*Rapanarivo, S.H.J.V., Lavranos, J.J., Leeuwenberg, A.J.M., and Röösli, W. <u>Pachypodium (Apocynaceae): Taxonomy, habitats and cultivation</u> "Taxonomic revision of the genus Pachypodium," S.H.J.V. Rapanarivo and J.J. Lavranos; "The habitats of Pachypodium species" S.H.J.V. Rapanarivo; "Cultivation" W. Röösli. (A.A. Balkema: Rotterdam, Brookfield, 1999) [Rapanarivo et al.]
 
*Rapanarivo, S.H.J.V., Lavranos, J.J., Leeuwenberg, A.J.M., and Röösli, W. <u>Pachypodium (Apocynaceae): Taxonomy, habitats and cultivation</u> "Taxonomic revision of the genus Pachypodium," S.H.J.V. Rapanarivo and J.J. Lavranos; "The habitats of Pachypodium species" S.H.J.V. Rapanarivo; "Cultivation" W. Röösli. (A.A. Balkema: Rotterdam, Brookfield, 1999) [Rapanarivo et al.]
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*Rowley, Gordon, D. Cactus Handbook 5: Pachypodium and Adenium (British Cactus and Succulent Society, (1983) 1999)
+
*Wikitionary: Terms
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*Rowley, Gordon. Didiereaceae: "Cacti of the Old World" (The British Cactus and Succulent Society [BSCS]: 1992)
+
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*Rowley, G.D. "The Pachypodium rosulatum aggregate (Apocynaceae) - one species or several?" <u>Bradleya: The British Cactus and Succulent Society Yearbook</u>. (16/1998)
+
{{pachypodium}}
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*Rapanarivo, S.H.J.V., Lavranos, J.J., Leeuwenberg, A.J.M., and Röösli, W. <u>Pachypodium (Apocynaceae): Taxonomy, habitats and cultivation</u> "Taxonomic revision of the genus Pachypodium," S.H.J.V. Rapanarivo and J.J. Lavranos; "The habitats of Pachypodium species" S.H.J.V. Rapanarivo; "Cultivation" W. Röösli. (A.A. Balkema: Rotterdam, Brookfield, 1999, p.5) [The rest of the list is based on Rapanarivo et al.(1999)]
 
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*Rapanarivo et al. (1999) p. 5.
 
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{{Commons|Pachypodium}}
 
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{{Pachypodium}}
 
  
 
[[Category:Apocynaceae]]
 
[[Category:Apocynaceae]]
 
[[Category:Flora of Madagascar]]
 
[[Category:Flora of Madagascar]]

Latest revision as of 05:16, 30 September 2007


Pachypodium brevicaule
Pachypodium brevicaule 1.jpg
Plant Info
Scientific classification
Kingdom: Plantae
Division: Magnoliophyta
Class: Magnoliopsida
Order: Gentianales
Family: Apocynaceae
Genus: Pachypodium
Species: P. brevicaule

Binomial name
Pachypodium brevicaule
Baker

Pachypodium brevicaule is a species of plant that belongs to the dogbane family Apocynaceae, which is now amplified by the inclusion of the milkweed family Asclepiadaceae -- an important union to botanists and horticulturalists interested in the alliance succulents.

Distribution

This plant is native to Madagascar, from the south of Antananarivo to the Itremo Mountains.

Habit

A flattened, tuberous, cactus-like plant with a very low trunk and a very wide, exaggerated diameter without substantive branching whatsoever with exception to several extremely short flattened "branch"-like nodes or rosettes of leaves.

Ecology

Pachypodium brevicaule Baker grows in open, deciduous Western forest of Madagascar in full sun on sandstone, rarely on granite, in crevices between outcrops of quartzite. With a pH. Level varying from 3.5 to 4.5, it is strictly adapted to growing in acid substrates. (That strictness to acidity seemingly has implications to its cultivation.) It is found in the evergreen Sclerophyllous (Uapaca) woodland or savanna zones dominated by scattered woody plants. It grows at altitudes of 1250-1900 (2000 m) m.

Associated plant species, site indicators, include Pachypodium densiflorum, P. eburneum (Apocynaceae), Aloe compressa, A. capitata, (Asphodelaceae), Euphorbia quartzicola (Euphorbiaceae), (Orchidaceae), (Graminaea), (Bryophyta), and Lichenes. It occurs in a region that receives an annual rainfall of 1354 mm with a number of 5 dry months. Average monthly temperatures varies from 9°C to 17°C. The yearly average temperature is higher; however, at 13°C to 18.4°C.

Vernacular Malagasy Common Name

"Tsimondrimondry" (Merina); "Kimondromondro" (Betsileo)

Morphology

Habit

Pachypodium brevicaule is unique to the genus in habit. It is considered a dwarf plant. It takes on a broad flattenened tuberous, cactus-like habit that has a very short trunk measuring 2 to 8 cm high and an exaggerated diameter that can reach 10 to 40 cm. When in flower the plant gains stature by reaching a height of 25 cm. Pachypodium brevicaule Baker barely, if all, "branches." Rather it seems to form protruding nodes or rosettes of leaves that ranch from 1 to 4 cm in length and 2 to 4 cm in width. In the "Botanical Key for the Genus Pachypodium," the character "without branches or branchlets" is a distinguishing morphological character to the species Pachypodium brevicaule's definition.

The bark is colored pale grey and is sometimes shiny. It has a smooth texture. The bark is about 2 to 4 mm thick, with the wood being greenish. The "branches" or, better said, nodes of rosettes of leaves, when fresh, have paired, rather soft, curved spines at their apices, measuring 2 to 9 mm long by 1 to 1.5 mm at the base. They are pale grey to pale brown. When young, they are pubescent and more or less flat.

Leaves

Pachypodium brevicaule has leaves that are confined to the apices of the branches or nodes and rosettes. The leaves are sessile, without a stem, petiolate--with a stalk--peduncle--the main axis of the inflorescence--or pedicel--the stalk of a single flower--or it is shortly petiolate--having a stalk. If it has a stalk, the petiole measures up to 2 mm long. It is sparsely pubescent, fuzzy. The leaf blade is herbaceous, not woody-like, and glaucous, covered in a very fine bloom or a fine powdery layer, when fresh and papery when dried. The blade is shaped ovate, broad and rounded at the base and tapering toward the end, to obovate, egg-shaped and flat with the narrow end attached to the stalk. It measures 11 to 30 mm in length by 6 to 12 mm in width. The apex of the blade is acuminate, narrowing to a slender point. The base is blunt or rounded. The blade of Pachypodium brevicaule Baker is glabrous, smooth, to sparsely pubescent, slightly hairy, on both sides, with impressed venation above, and with midrib and secondary veins prominent beneath. There are 15-30 pairs of secondary veins, which are straight at the base, upcurved at the apex, and forming an angle of 45-85° with the costa, or the midrib of a leaf. The tertiary, third-level, venation are reticulate, forming a web or a network like pattern.

Inflorescence

The inflorescence of Pachypodium brevicaule is sessile, with a stalk, or pedunculate, with the main axial stem to an inflorescence. It can be congested with up to 7 flowers where the inflorescence measures 2.5 to 15 cm in length by 2 to 6.5 cm in width. The peduncle, itself, is glaucous and covered in a fine bloom. It takes the shape of a terete, an elongated cylindrical form that is round in cross-section. The terete measures roughly up to 120 mm in length by 2 to 4 mm in width. The degree of pubescent varies on the peduncle from sparsely to fully hairy, pubescent. The pedicels, the stalk of a single flower, measures up to 8 mm long and is hairy, pubescent.

The bracts, modified leaves at the base of a pedicel of a flower, a peduncle, or a branch, are longer than the pedicels on Pachypodium brevicaule Baker. They are narrowly oblong, having a somewhat elongated form with approximately parallel sides, to obovate, egg-shaped and flat with the narrow end attached to the stalk. The bracts measure from 5 to 13 mm long by 1.5 to 3 mm wide.. At their apex, they are acuminate, tapering gradually to a sharp point, or acute, having a sharp point or tip. On the outside, the bracts are fully pubescent, hairy to slightly so. Inside they are less so.

Flowers

The sepals of Pachypodium brevicaule's flower are glaucous, having a fine bloom over the surface. This bloom covers the basal part of the corolla tube, the petals of a flower considered as a group or unit and usually of a color other than green, or the inner whorl of the perianth shaped like a tube. The sepals are connate, united to a structure of the same kind, i.e. other sepals, at the base for about 0.5 mm. They are narrowly ovate, broad and rounded at the base and tapering toward the end, or narrowly oblong, having a somewhat narrowly elongated form with approximately parallel sides. The sepals measure 6 to 11 mm long by 2 to 3 mm wide. At the apex, they are acuminate, tapering gradually to a sharp point, or acute, having a sharp point or tip. Outside the sepals are often glabrous and smooth; whereas inside in the lower part and near the apex, they are slightly pubescent, hairy.

Corolla

The corolla, the inner whorl of the perianth, is bright yellow. It measures 17 to 25 mm long in the mature bud and forms a comparatively wide broadly ovoid, shaped like an egg, ovate, head measuring 7 to 11 mm long by 5 to 8 mm wide. The apex of the bud is obtuse, having a blunt or rounded tip. Overall the bud is pubescent outside. The corolla lobes are not as hairy; however. Especially where the lobes and tubes are covered in bud, the surface is glabrous. The pubescent belt inside the corolla tube is 2 mm above to 1 mm below where the stamens are inserted, not emerging beyond the corolla tube. Otherwise the corolla tube is glabrous and smooth. It is shaped like a funnel, infundibuliform, at 12 to 18 mm long (1.63 times as large as the calyx and 1.05 to 1.36 times as long as the lopes) The basal of the corolla tube is almost cylindrical. It is 2 to 3 mm long by 2 to 2.5 mm wide above the base (0.15 to 0.18 times the entire length of the entire tube.) The upper part of the corolla tube is almost cylindrical. Yet it widens at the throat altering the cylindrical form. The upper part measures 10 to 15 mm long by 5 to 5.7 mm wide at the mouth. The lobes are obliquely obovate, having sides of unequal length or form, which are egg-shaped and flat with the narrow end attached to the stalk. At their apex, the lobe of Pachypodium brevicaule Baker are rounded. They measure 9 to 18 mm in length by 8.5 to 14 mm in width. (That is, in proportion, the lobes are 0.73 to 0.94 times as long as the corolla tube and 1.1 to 1.3 times as long as they are wide.)

Stamens

The stamens of Pachypodium brevicaule, with an apex of 4 to 9 mm below the mouth of the corolla tube, are inserted, meaning they do not extent beyond the corolla tube or mouth of the flower. They measure from the base 3.5 to 4 mm. (Proportionally they are 0.22-0.29 of the length of the corolla tube.) The stamens are the "male reproductive" organ of an angiospermous flowering plant.

The anthers, the part of the stamen, typically on top, which bears the pollen, commonly consisting of (1) two of four thecae, which contain the pollen and (2) a sterile region in between the connective that is very narrowly triangular. The anthers range in size for Pachypodium brevicaule from 4.7 to 5.2 mm long by 0.7 to 0.9 mm wide. (Proportionally, that is, they are 5.22 to 7.14 times as long as wide.) Inside, the anthers are pubescent and hairy at the base of the connective, the part of tissue in a stamen that separates the two thecae of an anther. As well, it is pubescent just below where stamens cohere with the pistil head, the fertile region of the flower.

Pistil

Composing the female reproductive organ, the pistil varies in length from 4.8 to 6.5 mm. Pubescent and hairy, the ovary measures ovary 1.5 to 1.9 mm long (x) by 1.3 to 1.6 mm wide (y) by 1.2 mm high (z). The disk in a pistil is the slightly thickened, or otherwise distinguished region, around the style in certain flowers that secret nectar. The disks of Pachypodium brevicaule Baker number 5 broad ovate glands that are broad and rounded at the base and tapering toward their end. These glands, for which either 2 or 2 pair can be partly fused together, are about half as long as the ovary. (Proportionally that 0.5 times 1.5 to 1.9 mm.).

The often cylindrical stalk-like portion connecting the stigma with the carpel or ovary, the style is slightly pubescent and hairy at the base for the taxon. The stigma is the top-most receptive region of the style, which often divided into stigma-lobes that are commonly wet by a sticky exudate that helps captures and nourish pollen grains. The carpel, furthermore, is the female organ of the angiospermous flower that consists of a modified leaf that contains the ovules. Several carpels can be fused together to from a compound ovary.

The slightly pubescent style for Pachypodium brevicaule measures 2.6 to 3.6 mm long. The pistil head, the separate part attached to the style, is 0.71 to 1.0 mm high. It composition is complex. Its basal part is 0.4 to 0.6 mm long by 0.4 to 0.6 mm wide. The central part is ring-shaped at 0.15 to 0.2 mm in length by 0.5 by 0.7 mm in width. And, its stigmoid apex measures 0.1 to 0.15 mm long by 0.3 to 0.5 mm wide. Each carpel contains approximately 50 ovules.

Fruit

The fruit of Pachypodium brevicaule has two separate mericarps that form an angle of 5-45° at its base. Sometimes it is possible to see flowers on the same inflorescence that has fruit. Mericarps are the parts of a "schizocarp" fruit, that becomes dry at maturity and subsequently splits or breaks into several smaller pieces--i.e. individual mericarp or seed. The mericarps are colored pale to dark brown with longitudinal lines outside and whitish inside when dried. The fruits are fusiform at 57 to 140 mm long (x) by 3 to 5 mm wide (y) by 2 to 4 mm high (z). They are obtuse, having a blunt or rounded tip, to acute, having a sharp point or tip, at the apex. The surface of the fruit is pubescent and hairy. The exterior wall is 1 mm thick.

Seeds

The seed of Pachypodium brevicaule Baker is pale brown. It is shaped in an elliptical manner. Its margin has a distinct broader that is revolute, rolled backward from the tip or margins to the undersurface, towards the hilar. The hilar pertains the hilum, which is a scar on a seed indicating the point of attachment to the funiculus, the stalk connecting a seed with the placenta. The seed measures 3.5 to 3.9 mm in length by 1.5 to 1.8 mm in width. The testa, the outer and normally hard and protective layer of the seed, is smooth. The coma of Pachypodium brevicaule Baker is straw-colored at 13 to 21 mm long. A coma is usually terminal tuft of hairs on a seed. In the case of Pachypodium, the coma allows the seed to be airborne, as that is its means of distribution. Whereas the embryo measures 3.2 to 3.5 mm in length, the cotyledons are 1.5 in length by 1.5 mm in width. The cotyledons are ovate in shape, meaning that they are broad and rounded at the base and tapering toward the apex. They are cordate, having a heart shape, at the base. The rootlet is 2 to 2.5 mm long by 1.2 mm wide. (Proportionately that is 1.3 to 1.6 times as long as cotyledons)

Literature

Pachypodium brevicaule Baker John Gilbert Baker published Pachypodium brevicaule in 1887 in Journ. Linn. Soc. Bot. 22: 503 (1887). In 1934, J. M. H. A. Perrier de la Bâthie published an account of the taxon in Bulletin de la Société Botanique de France. 81: 303 (1934). Pichon, in 1949, offers another account of Pachypodium brevicaule Baker in Mém. Inst. Sc. Madag. sér. B, 2: 122 (1949). The latest account, before Rapanarivo et al is provided by Friedrich Markgraf within, Fl. Madag. fam. 169: 299 (1976). The Species Type is: Madagascar, sin. loc., Baron 4412 (holotype The Herbarium of the Royal Botanical Garden at Kew, near London; isotype The Herbarium of the Laboratoire de Phanérogamis at Paris). Fig. 3, p. 18; Map 2, p. 12; Plates 8-10, opposite p. 17.

External sources

  • Eggli, Urs. (1993) Glossary of botanical terms with special reference to Succulent Plants. with German Equivalents (British Cactus & Succulent Society: United Kingdom)
  • Rapanarivo, S.H.J.V., Lavranos, J.J., Leeuwenberg, A.J.M., and Röösli, W. Pachypodium (Apocynaceae): Taxonomy, habitats and cultivation "Taxonomic revision of the genus Pachypodium," S.H.J.V. Rapanarivo and J.J. Lavranos; "The habitats of Pachypodium species" S.H.J.V. Rapanarivo; "Cultivation" W. Röösli. (A.A. Balkema: Rotterdam, Brookfield, 1999) [Rapanarivo et al.]
  • Wikitionary: Terms

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