Read about Primula in the Standard Cyclopedia of Horticulture
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Primula (Primula veris, the "first in spring," was an old appellation of one or more of the species). Primulaceae. Primrose. Low plants, for the most part herbaceous, mostly spring-blooming but a few kinds used for winter flowering, producing usually clusters of attractive flowers mostly in white, pink, and rose, but sometimes in red, blue, and yellow. Perennial (plant sometimes monocarpic or blooming but once), with monopetalous salverform fls. in clusters on scapes that arise from a radical cluster of simple entire or lobed lvs. : corolla-tube usually surpassing the 5-toothed or 5-cleft calyx; corolla with 5 spreading lobes, which are commonly notched or retuse at the end and more or less narrowed at the base; stamens 5, affixed to the corolla-tube: ovary 1-loculed, with many ovules on an axile placenta, and 1 undivided filiform style and a capitate stigma, dehiscent by 5-10 valves: bracts of the floral involucre sometimes lf.-like.: the fls. of some species are strongly dimorphic or trimor- phic,—the stamens and pistils of different lengths in different fls. of the same species (Fig. 3174). See Darwin's work, "The Different Forms of Flowers on Plants of the Same Species;" this polymorphism is associated with cross - pollination. Often the herbage is covered with a loose meal or farina or powder.— Primulas are natives to the N. Temp, zone, only one being known in the cold parts of S. Amer., one in Java, and sparingly in Afr. They are mostly boreal or alpine plants. About a score are native to the colder parts of N. Amer. Twenty-five years ago, Pax (Monographische Ubersicht uber die Arten der Gattung Primula, Leipzig, 1888, and in Engler's Bot. Jahrbucher, vol. 10), admitted 145 species. Pax & Knuth, in Engler's Das Pflanzenreich, hft. 22 (iv. 237), 1905, describe 208 species and many marked hybrids, and others have been recognized since that time. The number of species now known is upward of 300, with the greatest extension in China (about one-half the species), about 70-75 in the Himalayan region, and the remainder in Japan, N. Amer., Eu., and Eurasia. P. magellanica occurs in Patagonia, but is apparently not in cult. The latest horticultural treatment is by S. Mottet, Monographie du genre primevere, Paris, 1915; this work follows the systematic analysis of Pax & Knuth, which also is adopted herewith. The fancier of primules must also have the proceedings of the Primula Conference held in London in 1913, comprising botanical and horticultural discussions (Journ. Roy. Hort. Soc. 39). The discussion contains a full synonymy of the Chinese and other Asiatic species by Balfour and of European species by MacWatt. For cult, and horticultural descriptions (for England), the reader should consult H. M. Paul, "Handbook of the Hardy Primula," 1911. For evening primrose and Mexican primrose, see (Enofhera. Notwithstanding the volume of the recent literature, a comprehensive monograph is still lacking, due to tne great extension of the genus by contemporary explorers. Further collecting in the Himalaya-Thibet- China region will undoubtedly discover many more forms. The numbers of new species have made it necessary to extend and to recast the sections as defined by Pax & Knuth; but these have not yet been redefined and keyed at once in a connected treatment for the entire genus, and in a compilation like the present it is necessary to spread the Paxian groups as a tentative expedient, even if species of not very close relationship are brought together; in this compilation, the purpose is not so much to show botanical affinities as to make an effort to enable the consultant to identify given species. Even so, it can not be expected, in a genus so large, so variable, and in which so many of the species are recently discovered and little known, that the groups and keys will be always satisfactory to the student. Much change is likely to take place in the definition or recognition of species in the genus, as the many forms are more closely studied. In the present account, the characterizations of the species have been drawn so far as possible from the recent working authorities. The portraits are cited in the text under the names they bear in the different publications, and the author cannot vouch for the authenticity of all of them. The reference R. H. S., in the citation of portraits, is to the Journal of the Royal Horticultural Society. The date of introduction, given for some of the recent species, is the year in which they were brought into cultivation in Great Britain. The informal notes on culture, under the different species, apply mostly to Great Britain. Primulas are cool-climate or cool-season plants, mostly spring-bloomers. Many of them grow at very high altitudes, and depend on very special conditions for their perfect development. Several cultural groups of primulas may be recognized: (1) The alpine and sub- alpine section affords some of the most useful plants for rock and alpine gardens. The relatively little attention given to alpine gardens in this country is the reason for the neglect of these charming spring-flowering plants. In recent years, many species have been added to these outdoor primulas and great interest has arisen in them abroad. (2) The polyanthus class, comprising fully hardy spring-flowering plants, suitable for culture under ordinary garden conditions, and always popular in this country. To the same class belong the true cowslip (P. veris) and the oxlip (P. elatior), but these are rarely seen in our gardens in their pure form. All are easily propagated by division. (3) Yellow-flowered or purple-flowered verticillate-clus- tered outdoor species, of the P. imperialis and P. japonica type, some of which are hardy even in the northern states with some winter protection. (4) The true greenhouse species, represented by the old P. sinensis (Chinese primrose), the more recent P. obconica and the still more recent P. malacoides. These are Chinese species. The colors are of the cyanic series. (5) The auriculas of gardens, developed from P. Auricula. In Great Britain, much interest is now taken in new primulas, and very many species are more or less in cultivation, the larger part of them as fancier's subjects. Not many of them have been tried to any extent in this country, and it is commonly assumed that the American hot summers are against them. Many of them are easily grown from seed and can be carried over in pots in a frame, if they are not hardy or will not withstand the changeable conditions of the open winter. Some of the species do well in open light, but the larger number of the new kinds probably require protection from sun; the species demand an equable supply of moisture. Some of the species mentioned in this country for outdoor growing are P. Auricula, P. Beesiana, P. Bulleyana, P. capitata, P. cortusoides, P. denticulata, P. farinosa, P. frondosa, P. japonica, P. marginata, P. minima, P. pulverulenta, P. rosea, P. Sieboldii, P. sikkimensis, P. Veilchii. aside from the English primroses, oxlips, and cowslips (P. acaulis, P. elatior, and P. veris), and the auriculas. For the cultivation of the auricula, see Vol. I, page 430. Cultivation of hardy primulas. (E. J. Canning) The hardy primulas are not so well known in American gardens as they deserve to be, although their culture is gradually on the increase, and new species are occasionally introduced. Perhaps the best known and most commonly cultivated are those which are native to the meadow lands of Great Britain, central and northern Europe. These are the English primrose (P. acaulis), the cowslip (P. veris), the oxlip (P. elatior), and the polyanthus (P. Polyantha). They are all simple in their requirements, growing and flowering freely in any good garden soil, and are quite hardy as far north as Massachusetts at least, provided they are not planted in a too exposed or wind-swept position. They are all very attractive when in flower, and they can also be grown in pots and easily forced for flowering in the greenhouse in February and March. These primulas may be propagated by seeds or division. Seeds may be sown in February in pans or small shallow flats in a mixture of loam, leaf-mold, and sand of about equal proportions, making the surface very fine, pressing the seeds evenly into the soil and covering with about 1/4 inch of the finely sifted mixture. Place the flats or pans in a warm greenhouse or a temperature of 55° to 60° at night with a rise of 15° by day. In two or three weeks the seedlings should begin to appear. As soon as large enough to handle, they may be pricked out into other flats in a similar soil, and about 2 inches apart each way. By the middle of May they will be good plants, and since they do not flower the first season, they may be planted out in lines in some sheltered part of the garden till September, when they may be lifted and planted where they are wanted to flower in spring. Also those intended for flowering in the greenhouse should be potted at this time. Seeds may also be sown in a coldframe in April or May, scattering them very thinly in shallow drills, watering and keeping free from weeds in the summer, and transferring them in September to the position in the garden where they are to flower in the spring. Propagating by division is practised when the plants become rather large or to perpetuate some very fine variety. It consists simply in dividing the plant or clump into two or more parts and replanting again. September is the best month to do this. The cowslip, oxlip, and English primrose are excellent subjects for massing or naturalizing in open woodland, on sheltered banks, or any position where they are not too shaded, and where they can be left undisturbed for several years. They are almost indispensable in gardens where a spring display of flowers is wanted. A light mulching with stable-manure, or in very cold gardens, a few branches of hemlock or pine, is all the winter protection they need. Other hardy primulas not so well known as the above, but even more beautiful and showy and some of them of larger growth, are species from China and Japan, some of them from high altitudes in the Himalaya mountains, and others from boreal and mountainous regions of Europe and North America. From Japan, P. japonica and P. Sieboldii are the best. From China, P. pulverulenta and the recently introduced species, P. Bulleyana and P. Beesiana, are large and showy, producing their bright flowers in whorls, P. Beesiana having from five to eight whorls with an average of sixteen flowers in a whorl. From experience and observation, the writer finds that they must have a deep rich moist soil in a sheltered place, with an eastern aspect, or where they are shaded during the warmest part of the day. A low moist nook in a properly constructed rock- garden is an ideal place for them. The high mountain and northern species, P. cortusoides, P. denticulata and the variety cachemiriana, P. rosea, P. farinosa, P. mistassinica, and P. Auricula, require a rich moist soil with an eastern aspect in a rock-garden for their successful culture. It is not so much the cold of the winters as it is the heat and drought of our summers that makes their cultivation difficult. Most of them flower through the months of May and June. They are all propagated by seeds which may be sown in flats in a cool shaded frame as soon as ripe or about the end of July, wintering the seedlings in a cool greenhouse or frame the first winter, and planting out in the rock-garden in spring; or seeds may be sown in February in a warm greenhouse as recommended for the English primrose, but keeping the seedlings in flats in a shaded frame till September before planting in the rock-garden. A light dressing of decayed stable- manure carefully placed between the plants as winter comes on and a few hemlock or pine branches to protect them from the sun in winter are beneficial. While this last group of primulas may never become so popular in this country as they are in the cool and moist climate of England, yet, for anyone who can provide the conditions, they are well worth growing. Commercial culture of florist's primulas. (E. A. White) Primulas have long been regarded as important by commercial plant-growers. Their compact dwarf habit of growth and their freedom of flower production make them especially desirable. They have never been used extensively as cut-flowers, yet the flower-clusters of some species, such as P. obconica and P. malacoides, lend themselves well to artistic arrangement and are sold in limited numbers in the larger cities, usually in bunches of twenty-five sprays. P. Polyantha also produces sprays of blooms which are particularly attractive in spring when cut and arranged in a somewhat formal manner similar to bunches of trailing arbutus. The species most generally grown under glass for potted plants are P. obconica, P. sinensis, P. kewensis, and P. malacoides (fairy primrose); P. Forbesii (the baby primrose) is still sometimes grown. While P. sinensis in its varying varieties is still grown as a potted plant to a considerable extent, it is of less importance commercially than are P. obconica, P. kewensis, P. malacoides, and P. floribunda. P. sinensis var. stellata seems more in demand than the type. When taken from the greenhouses to a dwelling-house or aflower-store, the individual flowers of P. sinensis soon fade and the plants become unsightly. Retail dealers speak of them as "poor keepers." The most desirable varieties of P. sinensis are Crimson King, Pink Beauty, Reading Blue, Orange King, The Czar, The Duchess, Coral-Pink, Princess May, and Royal White. In the stellata group, White Star, Pink Star, Light and Dark Blue Star, and Giant Red Star are most frequently grown. P. malacoides and P. obconica, the latter in its several varieties, Kermesiana, Fire King, and Giant Red are probably the most important present-day primulas. Primulas are usually propagated yearly from seed. When very large plants for exhibition purposes are desired, the plants may be carried over a second year. Young plants are usually more productive of blooms, hence are more desirable. Seeds must be fresh. Primulas may also be propagated from cuttings. When large plants are desired for Christmas, the seed is sown in January. Later sowings may be made in February and March. Seed-pans should have a layer of broken crock in the bottom for drainage, and a little coarse material is placed above this. The seed- pan is then filled evenly full with a mixture of equal parts of leaf-mold and sand. This is compacted slightly, being careful to have the surface even. The top of the soil should not be over 1/8 inch below the top of the rim of the pan. If lower than this, the confined atmosphere about the seedlings may cause an attack of the "damp- ing-off" fungus. The seeds are then sown evenly and thinly over the surface and a thin covering of one-half finely sifted leaf-mold and sand, thoroughly mixed, is sprinkled evenly over the top. The seed-pans are then sprinkled with a fine spray, covered with glass, and placed in a partially shaded spot. As soon as the seedlings germinate, the glass should be removed. .The germination period in the life of primulas is a critical one, and temperature, light, and moisture require particular attention. When the seedlings have developed about three leaves, they should be transplanted. Small flats are preferable to pots. The seedlings are spaced about 1 1/2 inches each way. A soil compost of equal parts of leaf-mold and sand is excellent for the first transplanting. When the seedlings have developed about five leaves they should be potted into 2- or 2 1/4-inch pots. Care should be taken in this first potting and in subsequent repottings not to set the plants too deeply in the soil, as it causes the lower leaves to decay. The crown should be even with the soil. If it is above the soil, the plants will be inclined to topple over as they reach maturity and it may be necessary to stake them. At no time should the young plants be allowed to become pot-bound. Any check in their development during the rapid-growing period prevents the perfection of the plants. They should be repotted several times and the soil made a little richer each time by the addition of well-rotted cow-manure and bone-meal. About the tenth of June primulas may be put into a frame out-of-doors. A shaded glass sash should be put over them and raised about 2 feet above the frame. This gives excellent air circulation about the plants and makes them strong and stocky. In August the plants are repotted for the last time. Six-inch pots are mostly used. The soil at this time should be considerably heavier and richer than previously. A mixture of three parts leaf-mold, two parts finely chopped sod, one part, sand and one part well-rotted cow-manure with a liberal sprinkling of bone-meal makes an excellent soil for primroses. Watering should be carefully attended to in the summer months. About the middle of September the plants should be brought into the greenhouse and placed in a coolhouse where a night temperature of about 45° can be maintained. This low temperature induces a stocky healthy growth and subsequently large strong flower-spikes. After bringing the plants into the greenhouse, they should become accustomed gradually to full sunlight. After a few weeks in a coolhouse, the temperature may be gradually raised to 50° or even 60°; but the plants are better if grown in a low temperature. Index. acaulis, 102. americana, 143.auriculata, 129. admontensis, 2. amoenana, 62, 70,101.Baby Primrose, 85. adulterina, 25. angustata, 41.Balbisii, 34. alba, 83, 116. 168. angustidens, 171, 172.Balfouriana, 41. albocincta, 34. anisiaca, 102.barbicalyx, 63. algida, 128. apennina, 43.Beesiana, 169. Ailionii, 50. Arctotis, 3.begoniaeformis, 63. altaica. 98. Arendsii, 27.bella, 155. ambita, 63. Auricula, 34. bellidifolia, 124. grandia, 153. prolifera, 161. bellunensis, 34. gratissima, 166. pseudocapitata, 120. Berninae, 4. hazarica, 178. pseudodenticulata , 117. Bicolor, 168. Heeri, 13. pscudoelatior, 99. biflora, 5. helodoxa, 164. pseudomalacoides, 84. Bilekii, 6. helvetica, 20. pseudosikkimensis, 182. blattariformis, 67. heucherifolia, 68. pubescens, 20, 41. Boveana, 59. hirsuta, 41. pulchella, 195. Bowlesii, 7. Huteri, 14. pulchelloides, 196. brevicalyx, 132. imperialis, 161. pulcherrima, 116. brevifolia, 177. inflata, 97. pulverulents, 160,167. Brisciri, 28. integrifolia, 48, 132. prumilio, 134. Bulleyana, 163. intermedia, 15. Purdomii, 194. Buttercup, 56. intricata, 98. purpurea, 116, 191. cachemiriana, 116. involucrata, 131. pusilla, 113, 147. cadinensis, 42. Isabellina, 56. pycnoloba, 61. caerulea, 93. japonica, 168, 173. redolens, 92. calliantha, 180. Juliae, 104. Reidii, 111. calycina, 37. kashmiriana, 132. Reinii, 95. canescens, 97. Kaufmannianna, 77. rhaetica, 21. capitata, 115, 119. Kellereri, 16. rosea, 63, 141, 168. capitellata, 130. Kerneri, 17. rotundifolia, 65. carminata, 168. kewensis, 1. rubra, 102. carniolica, 52. kichanensis, 157. rufa, 91. carpathica, 98. Kitaibeliana, 47. Rusbyi, 175. cashmeriana, 116. Knuthiana, 135. salisburgenais, 22. caulescens, 102. langkongensis, 66. salmonea, 168. cernua, 110. latifolia, 53. sapphirina, 114. chartacea, 69. leucophylla, 100. saxatilis, 71. chinensis, 60. lichiangensis, 80. scotica, 144. ciliata, 34, 41. lilacina, 168. secundiflora, 8. clarkiaeflora, 62. Lindsayi, 30. semi-plena, 63. Clementinae, 157. Listeri, 65. semperflorens, 60. Clusiana, 39. Littoniana, 126. septemloba, 75. coccinea, 41. longiflora, 151. serratifolia, 162. Cockburniana, 165. longifolia, 129. sibirica, 132. cognata, 150. longituba, 179. Sibthorpii, 102. Columnae, 97. longobarda, 37. Sieboldii, 62. commutata, 44. lutea, 34. sikkimensis, 181. concinna, 149. luteola, 140. Silva-Taroucana, 31. conspersa, 133. macrocalyx, 97. simensis, 58. cordifolia, 98. magellanica, 148. similis, 34. coronaria, 97. magnifica, 141. sinensis, 60, 193. cortusoides,62,70,80. malacoides, 83. sinolisteri, 64. Cottia, 45. malvacea, 66. sinomollis, 74. Courtii, 58. Mandarina, 60. sonchifolia, 166. Cowslip, 97. marginata, 51. spectabilis, 36. cridalensis, 25. Maximowiczii, 188. spherocephala, 121. crispa, 115. megaseaefolia, 94. spicata, 105. Croussei, 102. membranifolia, 179. splendens, 168. Cusickiana. 197. micrantha, 25. stellata, 60. cynoglossifolia, 53. microdonta, 183. striata, 168. daonensis, 42. minima, 46. Stuartii, 185, 191. darialica, 138. minutissima, 86. Sturii, 23. davurica, 146. mistassinica, 147. suaveolens, 97. deflexa. 123. Miyabeana, 173. Sueptitzii, 32. Delavayi, 89. modesta. 145. suffrutescens, 200. dentitculata,115,116. mollis. 73. superba, 63. deorum, 55. Munroi, 131. szechuanica, 187. Dinyana, 18. Mureti, 18. tangutica, 189. discolor, 8. Muretiana, 18. Tewfikiana, 33. domestica, 97. muscaroides, 122. tibetica, 134. dryadifolia, 108. muscoides, 154. tosaensis, 96. efarinoaa, 137. nessensis, 117. Traillii, 131. elatior, 98. nivalis, 41, 190, 191. turkratanica, 192. elliptica, 139. 192, 193. tyrolensis, 49. elongata, 186. nivea, 41. umbrella, 158. Elwesiana, 88. obconica, 63, 65. undulata, 63. erosa, 115. oblanceolata, 172. uniflora, 112. exscapa, 41. Obristii, 34. Unique, 31,165. Facchinii, 9. oculata, 76. valmenona, 25. Fairy Primrose, 83. odorata, 97. variabilis, 103. farinosa, 143, 145, oenensis, 42. variegata, 116. 146. 147, 148, 192. officinalis, 97. Veitchiana, 79. Fauriei, 199. Olgae, 142. Veitchii, 79. filicifolia, 60. orbicularis, 184. venusta, 24. fimbriata, 60. 63. oreodoxa. 63. 71. Venzoi, 25. Fire Ball, 116. ovalifolia, 90. veris, 97, 102. Floerkeana, 10. Oxlip, 98. verticillata,57, 58,59. floribunda, 56. Palinuri, 35. Viali, 126. forida, 107. Pallasii, 98. villosa, 44. Forbesii, 85. pannonica, 97. Vilmoriniana, 63. Forrestii. 91. Parryi, 174. vinciflora, 87. Forsteri, 11. parva, 63. violodora, 72. Fortunei, 29. patens, 62. viscosa, 53. frondosa, 136. Paxiana, 82. vittata, 176. Gagnepainii, 68. pedemontana, 40. vochinensis, 26. Gambeliana, 152. petiolaris, 159, 160. rulgaris, 102. geraniifolia, 81. Petitmenginii, 63. Warei, 143. gigentea, 98. Peyritschii, 19. Watsonii, 125. Gillii, 106. pinnatifida, 109. Wattii, 106. Giraldiana, 122. plena, 83. Wilsonii, 171. glabra, 118. poculiformis, 63. Winteri, 160. glabrescens, 65. Poissonii, 170. Wulfeniana, 38. glaucescens, 37. Polyantha, 103. yunnanensis, 156. glutinosa, 54. polyneura, 78. Goeblii, 12. Portae, 8 gracilenta, 127. praenitens, 60. grandiflora. 56, 62, 63,70,119,141.
I. Plants of hybrid origin, of many kinds, more or less in cult. I. Hybrids, p. 2786. II. Plants of specific difference, representing wild or native species of Primula. I. Blossoms pedicellate, in super-posed umbels: lvs. mem-branaceous or papery, ser-rulate or denticulate XIX. Cankrienia. p. 2805. II. Blossoms very short-pedicelled or nearly sessile, mostly in simple umbels: lvs. usually coriaceous, obtusely dentic-ulate. XX. Callianthae., p. 2807. I. Hybrids And Reputed Hybrids. Several hybrid primulas have attained more or less prominence in cult, aside from those in the Vernales group (P. elatior-veris-acaulis set), and they are briefly described here ; P. kewensis is apparently the best known of them in cult. In a genus so vast and abounding in beautiful forms, many good cultural hybrids are to be expected, although the number of artificial ones is surprisingly small considering the number of species and the length of time some of them have been in cult. For an account of Primula hybrids in nature, see Farrer, Journ. Roy. Hort. Soc. 39:112-28; also the monograph by Pax & Knuth.
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Primula is a genus of 400-500 species of low-growing herbs in the family Primulaceae. They include primrose, auricula, cowslip and oxlip. Many species are grown for their ornamental flowers. They are native to the temperate Northern Hemisphere, south into high altitude tropical mountains in Ethiopia, Indonesia and New Guinea, and are also found in temperate southern South America.
Perennial primulas bloom mostly during the spring; their flowers can be purple, yellow, red, pink, or white. Generally, they prefer filtered sunlight. Many species are adapted to high alpine climates.
Both the common name and scientific name refer to it being the first (prime) "rose" to open in spring.
Primroses are used as food plants by the larvae of some Lepidoptera species including Large Yellow Underwing, Lesser Broad-bordered Yellow Underwing, Setaceous Hebrew Character and Silver-ground Carpet.
Some species of Primula are commonly known as polyanthus.
- Selected species