ACANTACEAE

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            1. SYSTEMATIC POSITION:
            Bentham & Hooker
            Division: Phanerogames (Seed Plants)
                  Class: Dicotyledones
                        Sub-class: Gamopetalae
                               Series: Bicarpellatae
                                     Order: Personales
                                            Family: Acanthaceae
           
            2. MORPHOLOGICAL CHARACTERS:
            Habit – Herbs or shrubs, often with cystoliths.
            Leaves – Opposite, simple, entire, exstipulate.
            Inflorescence – Cymes or spikes.
            Flower – Bisexual, zygomorphic, hypogynous with prominent bract and bracteoles.
            Calyx – Sepals 4 or 5, united, unequal, imbricate or valvate.
            Corolla – Petals 5, often bilabiate, imbricate or twisted.
            Androecium – Stamens 4, epipetalous, didynamous or 2, staminodes often present, anther dithecous, spurred hairy.
            Gynoecium – Carpel 2, syncarpous, stigma 2, ovary superior, bilocular, ovules 2 to many in each loculus, placentation axile.
            Fruit – A capsule, opening by two valves elastically dehiscent, rarely a drupe.
                   4. COMPARATIVE SYSTEMATIC POSITION AND AFFINITIES:
            Bentham & Hooker and Takhtajan have placed this family under the order Personales. Cronquist put it under the order Scrophulariales, while Engler & Prantl placed this family under the order Tubiflorae.
            Many taxonomists have thought that the Acanthaceae has been derived from the Scorphulariaceae. Hutchinson considered this family to be the most advanced amongst Personales.
            The Acanthaceae is related to the Bigoniaceae and Scorphulariaceae, but differs from them by possession of prominent bracts and bracteoles, imbricate calyx of unequal sepals, beaked ovary and exalbuminous seeds with curved embryo. It is alike to the Pedaliaceae in the presence of irregular flowers and the nature of fruits. It is closely allied to the Lamiaceae, but distinguished by the bracteates inflorescence, bilocular ovary, terminal style and many seeded capsule.
            5. ECONOMIC IMPORTANCE:
            The members of this family are important for their ornamental and medicinal values.
            1. Plants with ornamental values are – Tunbergia grandiflora, Acanthus mantanus, Justicia gendarussa, etc.
            2. Plants with medicinal values are – Andrographis paniculata, Adhatoda vasica, Phlagocanthus thyrsiflorus, etc.
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