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Acanthaceae
KAMAL AKHTAR MALIK & ABDUL GHAFOOR
Department of Botany, University of Karachi, Karachi
Perennial sometimes annual, suffrutescent, armed or unarmed herbs or shrubs, rarely climbers or small trees. Leaves exstipulate, usually simple, opposite-decussate, entire or undulate-dentate, rarely crenate-dentate or lobed, mostly with cystoliths on the upper surface, petiolate or sessile. Flowers commonly in dichasial cymes becoming monochasial, often in dense to lax spikes, racemes, panicles, sometimes fasciculate or verticilate, rarely solitary; sessile or pedicellate, bisexual, hypogynous, usually zygomorphic; bracts 1,2 or more, often coloured, frequently large, imbricate, persistent, rarely absent. Calyx usually gamosepalous, persistent, 4-5-lobed, lobes valvate or imbricate, sometimes spinescent or reduced to truncate or 10-15-dentate minute tube. Corolla gamopetalous, tube cylindrical or ventricose, the limb of 5, subequally spreading lobes or strongly 2-lipped; upper lip erect or suberect, entire or 2-fid rarely absent or fimbriate; the lower lip more spreading, 3-fid or 3-lobed, lobes imbricate or controrted. Stamens 4 and didynamous or 2, epipetalous, ascending below the upper lip; anthers dorsifixed, usually unequal in a stamen pair, dithecous or monothecous, thecae parallel, divergent or superposed, appendaged or bearded, longitudinally dehiscent; stamindodes 0-1-3. Ovary conical or oblong-cylindric, bicarpellate, syncarpous, superior, sessile or minutely stipitate, bilocular, placentation axile, rarely parietal, ovules 2-10 (-many) in each locule, in 1 or 2 vertical rows, rarely collateral, anatropous; style simple, filiform stigmas 1 or 2 minute. Fruits a bivalved, 2-loculed, clavate to elliptic-ovoid or oblong-cylindric, terete or compressed, usually ± stipitate capsule, elastically dehiscent from apex downwards, rarely drupaceous. Seeds mostly flattened and lenticular or discoid rarely globose or angular, borne on retinacula or papillae, testa smooth, rugose, echinate, tuberculate, glochidiate, appressed hairy or papillate, embryo with scanty or no endosperm.
A large family of nearly 250 genera and 2500 species, distributed mainly in the tropics and extending to Mediterranean, Australia and Southern U.S.A. In Pakistan it is represented by 18 genera and 60 specific and infraspecific taxa; of which 44 are native.
Acknowledgements: We are grateful to Dr. Heino Heine (Paris), Dr. R.K. Brummitt (Kew) and Mr. I.C. Hedge (Edinburgh) for kindly going through the manuscript and offering valuable suggestions for its improvement. The financial assistance received from the United States Department of Agriculture under P.L. 480 with the coordination of Pakistan Agriculture Research Council, Islamabad is thankfully acknowledged.
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| 1 |
Calyx truncate or obscurely 10-16-toothed. Capsule globose below, abruptly beaked in the upper part. Plants climbing or twining. [cultivated] |
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16 Thunbergia |
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Calyx not truncate, usually deeply 4-5-lobed . capsule oblong, ovoid or ellipsoid, basally stipitate or not. Plants erect, prostrate to procumbent or straggling. [wild or cultivated] |
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(2) |
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| 2 (1) |
Corolla 2-lipped or subequally 5-lobed, not indurated |
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(3) |
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Corolla one-lipped, the upper lip absent or rudimentary, indurated |
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1 Blepharis |
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| 3 (2) |
Corolla deeply to shallowly 2-lipped |
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(4) |
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Corolla subequally 5-lobed |
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(11) |
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| 4 (3) |
Fertile stamens 4 |
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(5) |
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Fertile stamens 2 |
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(7) |
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| 5 (4) |
Bracts spinescent or sharply acute |
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2 Lepidagathis |
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Bracts not spinescent or sharply acute |
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(6) |
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| 6 (5) |
Cystoliths absent. Anthers monothecous, dorsally hairy. Seeds on papilliform funicles. [cultivated] |
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3 Aphelandra |
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Cystoliths present. Anthers dithecous; thecae equal, glabrous. Seeds on hooked retinacula |
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4 Hygrophila |
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| 7 (4) |
Staminodes present |
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(8) |
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Staminodes absent |
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(9) |
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| 8 (7) |
Flowers in axillary fascicles or terminal dense heads. Bracts leafy |
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4 Hygrophila |
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Flowers in terminal or axillary panicles. Bracts not leafy [cultivated] |
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17 Graptophyllum |
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| 9 (7) |
Bracts partially united at the base, Capsule elastically dehiscent |
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5 Dicliptera |
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Bracts free at the base. Capsules not elastically dehiscent |
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(10) |
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| 10 (9) |
Flowers mostly in trichotomously branched lax panicles of cymes |
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6 Peristrophe |
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Flowers mostly in congested spikes or panicles, sometimes solitary or in thyrsoid cymes |
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7 Justicia |
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| 11 (3) |
Fertile stamens 4. Staminodes absent |
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(14) |
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Fertile stamens 2. Staminodes 2 |
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(12) |
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| 12 (11) |
Calyx 4-lobed, lobes imbricate |
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8 Barleria |
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Calyx 5-lobed, lobes valvate or contorted |
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(13) |
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| 13 (12) |
Corolla tube uniformly cylindrical, lobes contorted
or twisted. Bracts small and inconspicuous |
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9 Strobilanthes |
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Corolla tube cylindrical below, ventricose above,
lobes valvate. Bracts large and conspicuous.[cultivated] |
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18 Eranthemum |
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| 14 (11) |
Bracts present |
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10 Ruellia |
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Bracts present |
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(15) |
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| 15 (14) |
Calyx deeply 4-lobed, lobes clearly unequal, outer pair much larger than the inner. Bracts ciliate or spinescent |
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8 Barleria |
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Calyx 5-lobed, lobes equal or slightly unequal. Bracts neither ciliate nor spinescent |
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(16) |
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| 16 (15) |
Bracts 4-ranked, imbricated |
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(17) |
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Bracts neither 4-ranked, imbricated |
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(18) |
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| 17 (16) |
Stamens included; anthers monothecous, sterile cell bearded throughout. Capsule 4-seeded. [cultivated] |
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11 Crossandra |
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Stamens very slightly protruding; anthers dithecous, both thecae fertile, glabrous. Capsule 6-20-seeded |
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12 Hemigraphis |
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| 18 (16) |
Corolla lobes imbricate. Anther cells unequal. [cultivated] |
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13 Asystasia |
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Corolla lobes twisted or contorted. Anther cells equal |
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(19) |
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| 19 (18) |
Anthers bristle-tipped and sagittate at the bases. Capsule 2 or 4-seeded, elastically dehiscent |
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14 Petalidium |
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Anthers neither bristle-tipped nor sagittate, basally muticous. Capsule 4-20-seeded, not elastically dehiscent |
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(20) |
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| 20 (19) |
Leaves entire |
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(21) |
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Leaves crenate or toothed |
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(22) |
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| 21 (20) |
Bracts inconspicuous, usually linear, Capsule more
than 8-seeded |
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10 Ruellia |
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Bracts solitary, leafy. Capsule 4-8-seeded |
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9 Strobilanthes |
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| 22 (20) |
Ovary 8-12-ovuled. Flowers in sessile, congested
laxly borne clusters |
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15 Aechmanthera |
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Ovary 4-8-ovuled. Flowers in axillary or terminal,
interrupted spikes or panicles or capitate heads |
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9 Strobilanthes |
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List of lower taxa
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