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Family: Acanthaceae Juss.

Kingdom: Plantae Rank: Family Parent: Scrophulariales Status: Valid

Common Names:

  • ACANTHUS FAMILY - English, United States of America
  • WILD PETUNIA FAMILY - English, United States of America

Morphological Description

Family Recognition in the Field: Herbs (and 1 shrub) with opposite, simple, entire or indistinctly toothed leaves; flowers with sympetalous, 2-lipped or sometimes nearly radially symmetrical flowers in often bracteate inflorescences; stamens 2 or 4; fruit a capsule with seeds on small hook-like structures. In the somewhat similar Lamiaceae the fruits are of 4 one-seeded nutlets.

Diagnosis: Ours perennial herbs (some woody basally and 1 shrub) often with squarish stems; foliage of- ten with minute cystoliths (= mineral concretions) on surface; leaves opposite, sessile to petioled, simple; leaf blades entire or indistinctly toothed; stipules absent; flowers axillary or terminal, solitary or in peduncled spikes, cymes, or panicles; sepals 5, lanceolate or linear-lanceolate, united at base or up to 1/3 their length; corollas 2-lipped, or nearly radially symmetrical and 4-to 5-lobed, often with a color pattern; stamens 2 or 4; pistil 1; pistil of 2 carpels; ovary superior; style 1; fruit a capsule usually with 2 or 4 seeds; each seed typically supported by a small hook-like outgrowth (called a retinaculum or a jaculator)


Notes: A large (3,450 species in 229 genera), cosmopolitan, but mainly tropical family of mostly shrubs with some herbs, twiners, trees, and even aquatics; a number are used ornamentally including Acanthus, Justicia brandegeeana Wassh. & L.B. Sm. (SHRIMP-PLANT), and Thunbergia (CLOCKVINE). The family is closely allied to the Scrophulariaceae and some genera are intermediate between the two. Family name from Acanthus, BEARŐS-BREECHES, a genus of 30 mostly spiny xerophytic species of Old World tropical and warm areas; the leaf motif in the capitals of Corinthian columns supposedly originated from A. spinosus L. (Greek: acanthos, thorn, in reference to the spiny leaves and bracts) (subclass Asteridae)