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Project Name Data (Last Modified On 7/25/2013)
 

Flora Data (Last Modified On 7/25/2013)
Family ACANTHACEAE
Contributor L. H. DURKEE
Description Herbs, shrubs, vines or small trees. Leaves simple, opposite, exstipulate, often with cystoliths on the upper surface. Flowers irregular to nearly regular, perfect, borne in spikes, racemes, panicles, cymes or singly and often subtended by a conspicuous bract with 2 bracteoles; calyx synsepalous at least basally, persistent, the segments 5(4, 3); corolla gamopetalous, the limb 5-lobed or 2-lipped, rarely 1-lipped; stamens adnate to the corolla tube, 4 and didynamous or 2 only, the staminodes often present in flowers with 2 stamens, the anther cells 2 or 1, longi- tudinally dehiscent; ovary 2-celled, 2-10 ovules in each cell, the style filiform, simple, the stigmas 1 or 2. Fruit a capsule (except Mendoncia with drupaceous fruits), usually more or less stalked, 2-celled, 2-valved; seeds usually flattened, mostly borne on hook-shaped funicles, sometimes on papilliform funicles, the testa smooth or roughened, often mucilaginous when moistened.
Habit Herbs, shrubs, vines or small trees
Distribution The Acanthaceae includes about 250 genera and 2,500 species, mostly in the New and Old World tropics, with a few species extending into warm temperate regions.
Note The family is divided into 4 subfamilies according to Lindau (1895). More recent considerations have restricted the genera to be included in the family (Bremekamp, 1953, 1965). The Acanthaceae can be recognized by the prominent cystoliths appearing with magnification as small, cylindrical concretions or short lines on the upper surface of the leaves, the younger stems, the branches of the inflorescence, and the calyx. Genera lacking these are few and have exceptional features in the fruit. The genus Mendoncia is unique with a drupaceous fruit. The only genera lacking cystoliths and having the more typical capsular fruit with hooklike funicles are the genera Aphelandra and Megaskepasma. Seeds are frequently ejected forcefully by the hook-shaped funicle when the mature capsules are moistened by rainfall. In capsules that have opened the funicles can be seen with the naked eye as hook-shaped projections. Many species of the family also have conspicuous imbricate bracts subtending the flowers. These bracts may be green, yellow, bright red, or orange. While most genera of this family are restricted to either the New or Old World, a few are found in both. These include Justicia and Ruellia, the largest genera in the family with about 410 and 250 species respectively. Typically, most of these species are found in the tropics and subtropics with a few extending into temperate areas. The major economic importance of the family is horticultural. Cultivation is often restricted to greenhouses, however, since, although many genera have very attractive foliage and flowers, they are difficult to grow. Justicia guttata, the shrimp plant, with its showy spikes of reddish brown bracts is perhaps the best known in the United States. Seeds of Thunbergia alata, the clock vine or black- eyed Susan, are frequently sold in gardening stores in the United States, and in the tropics several other species of Thunbergia are grown as ornamentals. Several species of Ruellia are grown for their showy leaves and flowers. Fittonia and Strobilanthes are grown for sale. Many other genera are also cultivated and these include: Acanthus, Aphelandra, Crossandra, Eranthemum, Graptophyllum, Hypoestes, Justicia, Pachystachys, and Sanchezia.
Reference Bailey, L. H. 1951. Acanthaceae. In Manual of Cultivated Plants. Bremekamp, C. E. B. 1953. The delimitation of the Acanthaceae. Proc. Ned. Akad. Wetensh. C. 56: 533-546. Bremekamp, C. E. B. 1965. Delimitation and subdivision of the Acanthaceae. Bull. Bot. Surv. India 7: 21-30. Leonard, E. C. 1938. Acanthaceae. In P. C. Standley, Publ. Field Mus. Nat. Hist., Bot. Ser. 18: 1188-1263. 1951-1958. The Acanthaceae of Colombia. Contr. U.S. Natl. Herb. 31: 1-781. Lindau, G. 1895. Acanthaceae. In A. Engler & K. Prantl (editors), Die Nattr- lichen Pflanzenfamilien 4(3b): 274-354. Long, R. W. A. 1973. Biosystematic approach to generic delimitation in Ruellia (Acanthaceae). Taxon 22: 543-555. Wasshausen, D. C. 1973. New species of Aphelandra. Phytologia 25: 465-502. 1975. The genus Aphelandra. Smithsonian Contr. Bot. 18: 1-134.
Key a. Fertile stamens 4. b. Plants usually scandent; seeds not borne on hooklike funicles. c. Fruit a drupe ...... 21. Mendoncia cc. Fruit a beaked capsule with 2-4 seeds ...... 32. Thunbergia bb. Plants not scandent, usually erect herbs or shrubs; seeds borne on hooklike funicles or if on papilliform funicles, capsule not beaked. d. Seeds on papilliform funicles; seeds spheroidal, not flattened; cystoliths absent in leaves. e. Leaves small, under 4 cm long; corolla small, under 1 cm long ......  29 . Staurogyne ee. Leaves large, over 8 cm long; corolla larger, over 1 cm long ......  1. Aphelandra dd. Seeds on hooklike funicles; seeds flattened; cystoliths present in leaves, at least on upper surfaces (excepting Aphelandra). f. Anthers 2-celled in at least one pair of stamens. g. Upper pair of stamens with 2-celled anthers, one of the cells superposed, the shorter pair of stamens with 1-celled anthers; individual hairs of stems, leaves and bracts with a purplish band- ing pattern ...... 15. Herpetacanthus gg. Both pairs of stamens with 2-celled anthers, superposed or not; hairs of stem, leaves, and bracts lacking purplish banding pattern. h. Calyx segments very dissimilar, the posterior and anterior ones much larger than the lateral ones. i. Corolla 2-lipped, 5 mm long, white or violet; leaves under 10 cm long ...... 30. Teliostachya ii. Corolla with 5 nearly equal lobes, 15 mm long, yellow (purplish when dry); leaves over 10 cm long ...... 3. Barleria hh. Calyx segments similar or nearly so. j. Shrubs or small trees; calyx segments often rounded or obtuse at tip. k. Basal lobes of the anther rounded, not spurred; capsules 4-seeded, sericeous ...... 33. Tricanthera kk. Basal lobes of the anther spurred; capsules 8-seeded, glabrous ...... 5. Bravaisia jj. Herbs, often more or less suffrutescent (rarely shrubs;) calyx segments subulate or lanceolate, usually acute or acuminate. 1. Flowers solitary or fascicled; capsules without stalks, cylindrical; corollas 1 cm long or less. m. Corollas white; capsules with 12-16 seeds ......  16. Hygrophila mm. Corollas blue or pale purple; capsules with 2-4 seeds ...... 9. Dyschoriste 11. Flowers mostly in spikes, racemes, cymes, or pani- cles (excepting axillary flowers of Ruellia gemini- flora, R. praeclara, and R. metallica); capsules with stalks, clavate or elliptic; corollas over 1 cm long. n. Flowers in closely imbricate bracted, 4-sided spikes; bracts conspicuous, ovate. o. Leaves cordate; bracts indigo upon drying ......  14. Hemigraphis oo. Leaves ovate, lanceolate or oblong lanceo- late; bracts greenish upon drying ...... 4. Blechum nn. Flowers otherwise; bracts mostly inconspicuous and linear. p. Inflorescences in 1-sided racemes; corollas yellow with purplish throats ...... 2. Asystasia pp. Inflorescences in cymes, heads, panicles, spikes or flowers axillary; corollas variously colored, not yellowish with purple throats ......  27. Ruellia ff. Anthers 1-celled. q. Corolla bilabiate; stamens exserted with filaments over 10 mm long ...... 1. Aphelandra qq. Corolla lobes subequal, spreading; stamens included with fila- ments less than 5 mm long ...... 23. Neriacanthus aa. Fertile stamens 2. r. Anthers 1-celled. s. Corolla blue; upper lip of corolla over 15 mm long ...... 12. Habracanthus ss. Corolla orange or red; upper lip of corolla under 15 mm long. t. Bracts and bractlets conspicuously shorter than calyx segments (2-3 times); corolla beaked at tip prior to expansion ...... 18. Kalbreyeriella tt. Bracts and bractlets not conspicuously shorter than calyx segments (equal to or slightly longer); corolla not beaked at tip prior to expansion. u. Inflorescence a narrow, spike-like thyrse; some flowers borne in fascicles of 2 or 3 ...... 26. Razisea uu. Inflorescence paniculate; flowers all borne singly ...... 13. Hansteinia rr. Anthers 2-celled. v. Inflorescence condensed, head-like; bracts white-ciliate, linear subulate. w. Calyx segments 4; corolla ca. 15 mm long ...... 7. Chaetothylax ww. Calyx segments 5; corolla over 20 mm long ...... 6. Chaetochlamys vv. Inflorescence open, bracts otherwise. x. Cystoliths lacking in the leaves; seeds not borne on hook-like funicles. y. Bracts large and showy, over 30 mm long; corolla over 30 mm long ...... 20. Megaskepasma yy. Bracts small and inconspicuous, under 10 mm long; corolla under 15 mm long. z. Bracts stiff and awn-tipped; leaves mostly over 10 cm long ...... 10. Elytraria zz. Bracts flaccid and awnless; leaves mostly under 8 cm long ...... 22. Nelsonia xx. Cystoliths present in the leaves; seeds borne on hooklike funicles. A. Staminodes present. B. Anther cells basally spurred; flowers in fascicles of 6-8, loosely enclosed by bracts ...... 28. Sanchezia BB. Anther cells not basally spurred; flowers not in fascicles that are enclosed by bracts. C. Corolla limb equally or subequally 5-parted. D. Bracts conspicuous with spiny margins, over 2 cm long; calyx segments unequal ...... 3. Barleria DD. Bracts inconspicuous without spiny margins, under 1 cm long; calyx segments equal ...... 25. Pseuderanthemum CC. Corolla limb 2-lipped. E. Leaf blades mottled; corolla over 7 cm long; cultivated plants ...... 11. Graptophyllum EE. Leaf blades green; corolla under 6 cm long; mostly wild plants ...... 24. Odontonema AA. Staminodes absent. F. Outer bracts 4-ranked, large; flowers borne in very dense spikes. G. Bracts under 2 cm long; calyx segments similar ......  31. Tetramerium GG. Bracts over 2 cm long; calyx segments widely dissimilar ......  3. Barleria FF. Bracts not 4-ranked, usually small; flowers borne in lax spikes, panicles, cymes, or thyrses. H. Stems 6-angled in cross-section; calyx subtended by two partially united bracts ...... 8. Dicliptera HH. Stems rounded to 4-angled; bracts distinct. I. Calyx 5-parted. J. Bracts large, to 44 mm long ...... 20. Megaskepasma JJ. Bracts small, less than 20 mm long ...... 17. Justicia II. Calyx 3-parted ...... 19. Louteridium
 
 
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