Editing Acanthaceae (section)

==Description==
Plants in this family have simple, opposite, [[decussate]]d [[leaf|leaves]] with entire (or sometimes toothed, lobed, or spiny) margins, and without [[stipule]]s. The leaves may contain [[cystolith]]s, [[calcium carbonate]] concretions, seen as streaks on the surface.

The [[flower]]s are perfect, [[Floral symmetry|zygomorphic]] to nearly [[Floral symmetry|actinomorphic]], and arranged in an [[inflorescence]] that is either a [[raceme|spike]], [[raceme]], or [[cyme (botany)|cyme]]. Typically, a colorful [[bract]] subtends each flower; in some species, the bract is large and showy. The [[Sepal|calyx]] usually has four or five lobes; the [[Petal#Corolla|corolla]] tubular, two-lipped or five-lobed; [[stamen]]s number either two or four, arranged in pairs and inserted on the corolla, and the [[carpel|ovary]] is superior and bicarpellated, with axile [[placentation]].

The [[fruit]] is a two-celled [[capsule (fruit)|capsule]], [[Dehiscence (botany)|dehiscing]] somewhat explosively. In most species, the [[seed]]s are attached to a small, hooked stalk (a modified [[Ovule|funiculus]] called a [[jaculator]] or a retinaculum) that ejects them from the capsule. This trait is shared by all members of the clade [[Acanthoideae]]. A 1995 study of seed expulsion in Acanthaceae used high speed video pictures to show that retinacula propel seeds away from the parent plant when the fruits dehisce, thereby helping the plant gain maximum [[seed dispersal]] range.<ref>{{Cite journal|last1=Witztum|first1=A|last2=Schulgasser|first2=K|date=1995|title=The mechanics of seed expulsion in Acanthaceae|journal=Journal of Theoretical Biology|volume=176|issue=4|pages=531–542|doi=10.1006/jtbi.1995.0219|bibcode=1995JThBi.176..531W}}</ref>

A species well known to [[temperate]] gardeners is bear's breeches (''[[Acanthus mollis]]''), a herbaceous [[perennial plant]] with big leaves and flower spikes up to 2 m tall. [[Tropics|Tropical]] genera familiar to gardeners include ''[[Thunbergia]]'' and ''[[Justicia (plant)|Justicia]]''.

''[[Avicennia]]'', a genus of [[mangrove]] trees, usually placed in [[Verbenaceae]] or in its own family, [[Avicenniaceae]], is included in Acanthaceae by the [[Angiosperm Phylogeny Group]] on the basis of [[Molecular phylogenetics|molecular phylogenetic]] studies that show it to be associated with this family.