Hydrocera
Blume ex Wight & Arn.
Herbs, perennial, erect, glabrous, rather succulent, aquatic. Stems 5-angular, fistular in internodal region. Leaves spirally arranged, alternate, linear, serrate with a glandular leaf-base, exstipulate. Inflorescence axillary, cymose. Flowers on short axillary 1 - 5 (-10)-flowered cymes or in short axillary racemes. Sepals 5, petaloid, imbricate; two outer lateral ones flat, almost as large as petals, becoming anterior due to resupination; posterior produced into a short, hollow spur. Petals 5, free, two outer posterior ones longer, concave, coloured. Disk absent. Stamens 5; filaments short, broad and united towards connective; anthers connate around pistil. Ovary superior, 5-celled; stigmas 5, sessile and persisting in fruit; ovules 2 - 3 in each cell borne on axile placentae. Fruit Derry-like or pseudoberry, truncate at base and with a short bent beak of persisting stigmas, purplish-red; seed solitary in each cell, curved, corrugated; albumen absent; cotyledons plano-concave, thick; radicle short, superior.
India, Sri Lanka, S.E. Asia, Malay Peninsula and Java; chiefly at low altitudes in aquatic and marshy conditions; unitypic.
Notes. Backer & Bakhuizen (Fl. Java 1: 251. 1963) pointed out that Blume (Bijdr. 241. 1825) did not publish the generic name Hydrocera validly since he gave only the family description of Hydroceraceae and neither a generic description nor a specific one. Hydrocera was first validly published by wight & Arn. (Prodr. Fl. Pen. Ind. Orient. 140. 1834) but they cited Tytonia G. Don (Gen. Syst. Gard. Bot. 1:479. 1831) in synonymy, thus making Hydrocera Blume, superfluous and illegitimate. Hence, C.E. Wood (J. Arnold Arb. 56: 413 - 414. 1975) made a new combination : Tytonia triflora (L.) C.E. Wood based on Impatiens triflora L. Sp. Pl. 2: 938. 1753. However, the name Tytonia is not found in any of the subsequent taxonomic works and as such it becomes necessary to take steps to conserve the generic name Hydrocera.
Fruits of this genus have been variously described as a drupe (Bentham & Hooker, 1862-1893), a 5-seeded stone (Dunn, 1915), capsular berry (Venkateswarlu & Dutt, 1961) drupe-like berry (Hutchinson, 1979), 5-seeded indehiscent berry (Grey-Wilson, 1980), fleshy pseudoberry with a pentagonal berry-like drupe with the stone separating into one-seeded pyrenes (Cronquist, 1981) and berry with 5 stony seeds (Rama Devi & Narayana, 1990; Mamatha Raghuveer, Narayana & Dutt, 1993).
Literature. DURDANA YUNUS & P.K.K. NAIR. (1988). Pollen Morphology of Indian Geraniales 15 & 16: 30. GREY-WILSON, C. (1980). Studies in Balsaminaceae V: Hydrocera triflora, its floral morphology and relationship with Impatiens. Kew Bull. 35 (1): 213 - 219.; (1985). Balsaminaceae. In: DASSANAYAKA, M.D. Fl. Ceylon 5: 77-80 f. 1. MAMATHA RAGHUVEER, L.L. NARAYANA & B.S.M. DUTT, (1993). Dehiscent fruit of Hydrocera triflora (Linn.) Wt. & Arn. (Balsaminaceae): Its anatomy and dispersal. Rheedea 3(1): 12 - 14. NAIR, N.C., P.V. SREEKUMAR & V. J. NAIR (1981). J. Econ. Tax. Bot. 2: 224. NARAYANA, L.L. (1963). Contribution to the embryology of Balsaminaceae I. J. Indian Bot. Soc. 42: 102 - 109; (1965). Contribution to the embryology of Balsaminaceae II. J. Jap. Bot. 40: 104 - 116; (1974). A contribution to the floral anatomy of Balsaminaceae. Ibid. 49: 315 - 320. RAMADEVI, D. & L.L. NARAYANA, (1989). Floral anatomy of Balsaminaceae. In: TRIVEDI, M.L., B.S. GILL & S.S. SAINI (Eds.). Aspects of Plant Science 12: 707 - 719.; RAMADEVI & L.L. NARAYANA. (1990). Morphology of the flower and fruit of Hydrocera triflora Wight & Arn. emend. Venkat. and Dutt an elucidation. Proc. Indian Acad. Sci. (Plant Sci.) 100: 43 - 49. SUBRAMANYAM, K. 1962. Aquatic Angiosperms. 12. f. 7. VENKATESWARLU, J. & L. LAKSHMINARAYANA. (1957). A contribution to the embryology of Hydrocera triflora Wt. & Arn. Phytomorphology 7: 194 - 203. VENKATESWARLU, J. & B.S.M. DUTT. (1961). Amended description of Hydrocera triflora Wight & Arn. J. Bombay Nat. Hist. Soc. 58: 545 - 547. WOOD, C.E. (1975). The Balsaminaceae in the Southeastern United States. J. Arn. Arb. 56: 413 - 426.
India, Sri Lanka, S.E. Asia, Malay Peninsula and Java; chiefly at low altitudes in aquatic and marshy conditions; unitypic.
Notes. Backer & Bakhuizen (Fl. Java 1: 251. 1963) pointed out that Blume (Bijdr. 241. 1825) did not publish the generic name Hydrocera validly since he gave only the family description of Hydroceraceae and neither a generic description nor a specific one. Hydrocera was first validly published by wight & Arn. (Prodr. Fl. Pen. Ind. Orient. 140. 1834) but they cited Tytonia G. Don (Gen. Syst. Gard. Bot. 1:479. 1831) in synonymy, thus making Hydrocera Blume, superfluous and illegitimate. Hence, C.E. Wood (J. Arnold Arb. 56: 413 - 414. 1975) made a new combination : Tytonia triflora (L.) C.E. Wood based on Impatiens triflora L. Sp. Pl. 2: 938. 1753. However, the name Tytonia is not found in any of the subsequent taxonomic works and as such it becomes necessary to take steps to conserve the generic name Hydrocera.
Fruits of this genus have been variously described as a drupe (Bentham & Hooker, 1862-1893), a 5-seeded stone (Dunn, 1915), capsular berry (Venkateswarlu & Dutt, 1961) drupe-like berry (Hutchinson, 1979), 5-seeded indehiscent berry (Grey-Wilson, 1980), fleshy pseudoberry with a pentagonal berry-like drupe with the stone separating into one-seeded pyrenes (Cronquist, 1981) and berry with 5 stony seeds (Rama Devi & Narayana, 1990; Mamatha Raghuveer, Narayana & Dutt, 1993).
Literature. DURDANA YUNUS & P.K.K. NAIR. (1988). Pollen Morphology of Indian Geraniales 15 & 16: 30. GREY-WILSON, C. (1980). Studies in Balsaminaceae V: Hydrocera triflora, its floral morphology and relationship with Impatiens. Kew Bull. 35 (1): 213 - 219.; (1985). Balsaminaceae. In: DASSANAYAKA, M.D. Fl. Ceylon 5: 77-80 f. 1. MAMATHA RAGHUVEER, L.L. NARAYANA & B.S.M. DUTT, (1993). Dehiscent fruit of Hydrocera triflora (Linn.) Wt. & Arn. (Balsaminaceae): Its anatomy and dispersal. Rheedea 3(1): 12 - 14. NAIR, N.C., P.V. SREEKUMAR & V. J. NAIR (1981). J. Econ. Tax. Bot. 2: 224. NARAYANA, L.L. (1963). Contribution to the embryology of Balsaminaceae I. J. Indian Bot. Soc. 42: 102 - 109; (1965). Contribution to the embryology of Balsaminaceae II. J. Jap. Bot. 40: 104 - 116; (1974). A contribution to the floral anatomy of Balsaminaceae. Ibid. 49: 315 - 320. RAMADEVI, D. & L.L. NARAYANA, (1989). Floral anatomy of Balsaminaceae. In: TRIVEDI, M.L., B.S. GILL & S.S. SAINI (Eds.). Aspects of Plant Science 12: 707 - 719.; RAMADEVI & L.L. NARAYANA. (1990). Morphology of the flower and fruit of Hydrocera triflora Wight & Arn. emend. Venkat. and Dutt an elucidation. Proc. Indian Acad. Sci. (Plant Sci.) 100: 43 - 49. SUBRAMANYAM, K. 1962. Aquatic Angiosperms. 12. f. 7. VENKATESWARLU, J. & L. LAKSHMINARAYANA. (1957). A contribution to the embryology of Hydrocera triflora Wt. & Arn. Phytomorphology 7: 194 - 203. VENKATESWARLU, J. & B.S.M. DUTT. (1961). Amended description of Hydrocera triflora Wight & Arn. J. Bombay Nat. Hist. Soc. 58: 545 - 547. WOOD, C.E. (1975). The Balsaminaceae in the Southeastern United States. J. Arn. Arb. 56: 413 - 426.
