|Flowers of Odontonema cuspidatum|
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, Brazil 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.
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, calcium carbonate concretions, seen as streaks on the surface.
The flowers are perfect, zygomorphic to nearly actinomorphic, and 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 Bear's Breeches (Acanthus mollis ), a herbaceous perennial plant with big leaves and flower spikes up to 2m tall. Tropical genera familiar to gardeners include Thunbergia and Justicia.
Avicennia, a genus of mangrove tree, 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).
Excluded genera 
|Wikimedia Commons has media related to: Acanthaceae|
|Wikispecies has information related to: Acanthaceae|
- "Family: Acanthaceae Juss., nom. cons.". Germplasm Resources Information Network. United States Department of Agriculture. 2003-01-17. Retrieved 2011-07-29.
- "Acanthaceae". Integrated Taxonomic Information System. Retrieved 2011-07-29.
- Wortley, A.H., Harris, D.J. & Scotland, R.W.; 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.
- "GRIN genera sometimes placed in Acanthaceae". Germplasm Resources Information Network. United States Department of Agriculture. Retrieved 2011-07-29.
- 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.