Acanthaceae

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Read about Acanthaceae in the Standard Cyclopedia of Horticulture 

Acanthaceae (from the genus Acanthus, derived from the Greek, a spine; some of the plants are spiny). Acanthus Family. Fig. 54. Herbs, or rarely shrubs or trees: leaves opposite, rarely whorled: flowers bisexual, irregular, usually bilabiate; calyx 5-cleft; corolla 5-lobed, gamopetalous, hypogynous, the lobes imbricated; stamens usually 4, didynamous, rarely 2, sometimes a staminodium present, epipetalous; hypogynous disk present, mostly small; ovary superior, 2-celled, each cell 2-4-, rarely many-, ovuled; style 1; stigmas 1-2, one lobe often small or wanting: fruit a capsule; seeds exalbuminous, aided in distribution by peculiar outgrowths of the funiculus.

Acanthaceae has 173 genera and about 1,500 species, of tropical distribution. Few species extend into the Mediterranean region and into the United States. Six species are found in the northeastern United States. Two hundred species belong to the genus Ruellia, and 250 to Justicia. The family is related to the Bignoniaceae, and to the Scrophulariaceae, as well as to the other families of this group. The 2-celled ovary with 2-4 ovules and the queer outgrowths of the funiculus are distinctive.

Many species are used in the tropics for medicine; for example, Asteracantha longifolia, a purge and sudorific; Justicia Gendarussa, astringent, used in India for rheumatism, and the leaves sprinkled in clothing to keep insects away; Justicia pectoralis, used for lung troubles. The young flowers of Blepharis edulis and Asystasia gangetica are eaten as vegetables. Ruellia ciliosa of the United States has recently been sold spuriously as Spigelia (pink root).

Twenty to 30 genera are in cultivation in N. America, except in a few cases, as ornamental greenhouse plants. Among these are: Acanthus (Bear's Breech), hardy herbs; Adhatoda, shrubs; Aphelandra, shrubs; Crossandra, shrub; Fittonia, herbs; Graptophyllum (Caricature Plant), shrubs; Jacobinia, herbs; Justicia, referred to other genera; Peristrophe; Ruellia, herbs or shrubs; Strobilanthes, often used also for bedding.

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Acanthaceae
Flowers of Odontonema cuspidatum
Flowers of Odontonema cuspidatum
Plant Info
Scientific classification
Kingdom: Plantae
Division: Magnoliophyta
Class: Magnoliopsida
Order: Lamiales
Family: Acanthaceae
Juss.

Genera
See text.

The family Acanthaceae (or Acanthus family) is a taxon of dicotyledonous flowering plants containing almost 250 genera and about 2500 species.

Most are tropical herbs, shrubs, or twining vines; some are epiphytes. Only a few species are distributed in temperate regions. The four main centres of distribution are Indonesia and Malaysia, Africa, Brasil and Central America. The representatives of the family can be found in nearly every habitat, including dense or open forests, in scrublands, on wet fields and valleys, at the sea coast and in marine areas, and in swamps and as an element of mangrove woods.

Justicia aurea

Plants in this family have simple, opposite, decussate leaves with entire (or sometimes toothed, lobed, or spiny) margins, and without stipules. The leaves may contain cystoliths, or calcium carbonate concretions, seen as streaks on the surface. The flowers are perfect, zygomorphic to nearly actinomorphic, these arranged in an inflorescence that is either a spike, raceme, or cyme. Typically there is a colorful bract subtending each flower; in some species the bract is large and showy. The calyx is usually 4-5 lobed; the corolla tubular, 2-lipped or 5-lobed; stamens either 2 or 4 arranged in pairs and inserted on the corolla; and the ovary superior, 2-carpellate, with axile placentation. The fruit is a two-celled capsule, dehiscing somewhat explosively. In most species, the seeds are attached to a small, hooked stalk (a modified funiculus called a jaculator) that ejects them from the capsule.

A species well-known to temperate gardeners is Acanthus mollis or Bear's breeches, a herbaceous perennial plant with big leaves and flower spikes up to 2 m tall. Tropical genera familiar to gardeners include Thunbergia and Justicia.

Avicennia, usually placed in Verbenaceae or in its own family, Avicenniaceae, is included in Acanthaceae by the Angiosperm Phylogeny Group on the basis of molecular phylogenetic studies that show it to be associated with this family.

Selected genera

There are 246 accepted genera according to Germplasm Resources Information Network (GRIN).

Photo Gallery

References

  1. ↑ Wortley, A.H., Harris, D.J. & Scotland, R.W. (2007). "On the Taxonomy and Phylogenetic Position of Thomandersia.". Systematic Botany 32 (2): 415-444. doi:10.1600/036364407781179716. 
  • Schwarzbach, Andrea E. and McDade, Lucinda A. (2002). "Phylogenetic relationships of the mangrove family Avicenniaceae based on chloroplast and nuclear ribosomal DNA sequences". Systematic Botany 27: 84–98. 

External links

  • Acanthaceae in L. Watson and M.J. Dallwitz (1992 onwards). The families of flowering plants: descriptions, illustrations, identification, information retrieval.
  • Tree of Life Acanthaceae
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