Acanthaceae: Characters and Affinity | Dicotyledons | Botany

In this article we will discuss about:- 1. General Characters of Acanthaceae 2. Floral Formula of Acanthaceae 3. Number and Distribution 4. Common Plants 5. Affinity and Economic Importance.   

General Characters of Acanthaceae:

Plants—perennial herbs of shrubs, sometimes climbing, (e.g., Thunbergia), rarely trees (e.g., Strobilanthus), with branches swollen at the nodes. Leaves—opposite and decussate, simple, entire, often with cystoliths, exstipulate. Inflorescence—racemose (dense spike) or cymose, often with copious bracts and bracteoles. Flowers—zygomorphic, bisexual, hypogynous, bracteate.

Sepals—(5), often unequal, much reduced (e.g., Thunbergia), usually imbricate. Petals—(5), often bilabiate, sometimes oblique, imbricate or twisted. Stamens—4, didynamous, sometimes 2 (e.g., Fusticia, Adhatoda, etc.), epipetalous, sometimes 1-3 staminodes present; anthers sometimes spurred and hairy.

Carpels—(2), medianly placed; ovary superior, beaked (pro­longed but does not bear any ovule), 2-celled, with 2 or more anatropous ovules in each cell on the axile placenta; style simple, terminal; stigma often unequal, sometimes spoon-shaped. Fruit—usually a loculicidal capsule. Seeds—generally supported on a development (often hook-like) of the funicle (jaculator), exalbuminous. Embryo—curved, radicle pointed downwards.

Floral Formula of Acanthaceae:

Number and Distribution of Acanthaceae:

This family consists of about 240 genera and over 2,200 species which are commonly found in the tropical regions.  

Common Plants of Acanthaceae:

(1) Adhatoda vasica Nees., a common densely growing erect shrub.

(2) Barleria prionitis L., a shrub, commonly found in bushes with two prolonged thorns at each node.

(3) Barleria cristata L., an erect undershrub.

(4) Hygrophila spinosa T. And. = Asteracantha longifolia Nees., an erect highly spinous marshy herb extensively used as a remedy for diarrhoea; H. phlomoides Nees., an erect herb without any spine, commonly found in wet places.

(5) Andrographis paniculata Nees., a common herb with square stems used as a febrifuge and liver tonic; A. echioides Nees., common in waste places and on old brick walls.  

(6) Fusticia gendarussa L., often planted in gardens.

(7) F. simplex Don., F. diffusa Willd. and F. procumbens = Rostellularia pro- cumbens Nees., are common weeds; F. betonica L., an erect shrub with pale-violet flowers, often planted in gardens.

(8) Ruellia pros­tata Lamk. = Dipteracanthus prostratus Nees., and R. tuberosa L. = Dipteracanthus tuberosus Nees., very common in and about gardens.

(9) Cardenthera triflora Ham., a weed of marshy places.

(10) Ecbolium linneanum Kurz., a small shrub commonly found in bushes and road­sides.

(11) Nelsonia campestris R. Br., a diffuse herb found on grassy lands.

(12) Thunbergia grandiflora Roxb., a big twining plant planted in gardens.

(13) Acanthus ilicifolius L., a very prickly mangrove plant.

(14) Rungia parviflora Nees., a common procumbent weed bearing one-sided spike.

(15) Rhinacanthus communis Nees., a garden plant.

(16) Dicliptera roxburghiana Nees., a common weed.

(17) Hemi­graphis hirta T. And., H. latebrosa Nees., and Phaylopsis parviflora Willd. = Micranthus oppositifolius Wendl., are common weeds of grassy lands.

(18) Crossandra undulifolia Salisb., a small shrub.  

(19) Eranthemum platiferum Nees. = Daedalacanthus platiferus Gamble, a perennial undershrub.

(20) Lepidagathis hyalina Nees. = L. incurva D. Don., a sub-erect perennial herb, occasionally found.

(21) Peristrophe bicalyculata Nees., a paniculately branched herb with 6-angled stems.

(22) Ebermaiera glutinosa Wall., a trailing herb found in rice-fields.

(23) Strobilanthes auriculatus Nees. = Pteracanthus auricularis Bran., a shrub; S. scaber Nees. = Sericocalyx scaber Nees., a herb.

(24) Asystasia gangetica T. And., a procumbent perennial weed found near the banks of the Ganges.

Affinity and Economic Importance of Acanthaceae:

This family is closely allied to Scrophulariaceae and Bignoniaceae but readily distinguished by the presence of cystoliths in leaves, copious bracts and bracteoles, imbricated calyx of unequal sepals, 2-celled beaked ovary and exalbuminous seeds with jaculator and curved embryo. It differs from Labiatae by its 2-celled unlobed ovary, terminal style, many-seeded capsule and bracteated inflo­rescence.

Economic Importance of Acanthaceae:

This family is of little economic importance. Adhatoda vasica and Hygrophila spinosa are used in Kabiraji medicine. Andrographis paniculata is used as a liver tonic for children. Some plants are ornamen­tals, such as, Acanthus, Barleria, Ruellia, Thunbergia, Fustica, Facobinia, etc.