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The Family Acanthaceae Juss. (Acanthus family) is a taxon of dicotyledonous flowering plants containing some 234-250 genera and about 2500 species. Most are tropical herbs, shrubs, or twining vines; some are spiny. Only a few species are distributed in temperate regions.

Plants in this family have simple, opposite, decussate leaves with entire (or sometimes toothed or lobed) margins. The leaves may contain cystoliths, seen as streaks in the surface. 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. Seeds non-endospermous with large embryos.

A species well-known to temperate gardeners is Acanthus mollis or Bear's breech: perennials with big (up to 1 m or 3 ft tall) leaves and equally tall flower spikes. Tropical genera familiar to gardeners include Thunbergia and Justicia.

Genera

  Acanthus L. -- bear's breech
  Andrographis Wallich ex Nees -- false waterwillow
  Anisacanthus Nees -- Desert honeysuckle
  Aphelandra R. Br.
  Asystasia Blume
  Barleria L. -- Philippine violet
  Barleriola Oerst.
  Blechum P. Br.
  Carlowrightia Gray -- wrightwort
  Dicliptera Juss. -- foldwing
  Dyschoriste Nees -- snakeherb
  Elytraria Michx. -- scalystem
  Eranthemum L.
  Graptophyllum Nees
  Hemigraphis Nees
  Henrya Nees ex Benth.
  Holographis Nees
  Hygrophila R. Br. -- swampweed
  Hypoestes Soland. ex R. Br.
  Justicia L. -- justica, water-willow
  Nelsonia R. Br.
  Odontonema Nees -- toothedthread
  Oplonia Raf.
  Pachystachys Nees
  Pseuderanthemum Radlk.
  Ruellia L. -- wild petunia
  Sanchezia Ruiz & Pavón
  Siphonoglossa Oerst. -- tubetongue
  Stenandrium Nees -- shaggytuft
  Teliostachya Nees
  Tetramerium Nees
  Thunbergia Retz.
  Yeatesia Small -- bractspike
and about 200 more.
Ref: ITIS 34350 2002-09-07
For full list, see Kew