Senna siamea (Lam.) H.S.Irwin & Barneby
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Authors
Howard S. Irwin, Rupert C. Barneby
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Authority
Irwin, Howard S. & Barneby, Rupert C. 1982. The American Cassiinae. A synoptical revision of Leguminosae tribe Cassieae subtrib Cassiinae in the New World. Mem. New York Bot. Gard. 35, part 1: 1-454.
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Family
Caesalpiniaceae
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Scientific Name
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Type
Holotypus, labelled C. siamea but without further data of origin, P (hb. Lamk.)!—Sciacassia siamea (Lamarck) Britton ex Britton & Rose, N. Amer. Fl. 23(4): 252. 1930.
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Synonyms
Cassia siamea Lam., Sciacassia siamea (Lam.) Britton, Cassia florida Vahl, Cassia gigantea Bertero ex DC., Cassia arborea Macfad., Cassia siamea var. puberula Kurz
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Description
Species Description - Amply leafy, precociously flowering trees of rapid growth, regenerating by suckers when felled, with almost smooth gray bark and dense rounded (when old misshapen) crown of foliage, at anthesis (3-)6-20(-30) m but in the Neotropics seldom exceeding 15 m, the hornotinous branchlets subterete lenticellate, these with lf-stalks and axes of inflorescence ± densely strigulose-pilosulous with fine appressed, ascending or erect hairs up to 0.05-0.2 mm, the foliage bicolored, the stiffly chartaceous lfts above lustrously dark olivaceous, always glabrous, beneath paler dull and minutely strigulose either along veins only or overall, the inflorescence an exserted or basally leafy-bracteate, either narrowly thyrsiform or pyramidal panicle of densely many-fld racemes, its main axis ±1-4 dm. Stipules very early caducous subulate ±1 mm, absent from most spms. Lvs 1-3(-3.5) dm, those of vigorous leafy shoots often longer and more complex than those near or at base of panicle; petiole including discolored but not much swollen pulvinus (1.5-)2-3.5 cm, at middle 1-1.8 mm diam, terete except for shallow open ventral groove; rachis (4.5-)6-21(-25) cm, the longer inter-fo- liolar segments 1.3-2.7(-3) cm; petiolar glands 0; pulvinules 2-3.5 mm; lfts 5-12(-14) pairs, of subequal length or commonly longest near or beyond middle of rachis and diminished toward base or toward both ends, in outline symmetrically lance-, oblong- or ovate-elliptic obtuse mucronulate or (when relatively broad) ovate or obovate emarginate, the largest 4-8 x (1.1-) 1.4-2.7(-3) cm, (1.8-)2-3.5(-4) times as long as wide, at base symmetrically rounded or broadly cuneate, the margin plane, the straight centric midrib immersed or shallowly depressed above, stoutly cariniform beneath, the 8-14 major camptodrome with many intercalary secondary veins, connecting tertiary and fine reticular venules all subequally prominulous on both faces. Racemes ±(10-)20-60-fld, at anthesis corymbiform, the open fls elevated beyond the succeeding buds, the axis including short stout peduncle becoming (3-)4-9 cm; bracts spreading-incurved, linear-elliptic 3-6 mm, near middle abruptly dilated or sublobulate, closely conduplicate, deciduous by full anthesis; pedicels at full anthesis and afterward (2-)2.2-3.5 cm; sepals successively explanate during anthesis, finally subreflexed, all orbicular or almost so, carnosulous and hence wrinkled when dried, either yellow or more commonly fuscous, the 2 outer ones 4-6(-7) mm, the inner 6.5-9 mm; petals yellow glabrous, oblong-obovate beyond the short claw, subhomomorphic except the vexillar one often a little smaller and the 2 abaxial ones a little longer than the rest, the longest (10-) 12- 17 mm; androecium glabrous, functionally 7-merous but the staminodes relatively large, their thecae 2.2-3 x 1.3-1.8 mm; filaments of 4 median stamens 2.5-4 mm, of the central abaxial one 4.5-5.5, of 2 latero-abaxial ones 7-12 mm, the anthers of 4 median and central abaxial one 5-6 mm, of 2 latero-abaxial ones 5.5-8 mm, the anthers all lanceolate in outline, scarcely beaked, bluntly sagittate at base, dehiscent by a wide U-shaped slit sometimes divided by a tongue-like septum; ovary densely velutinous; style glabrous, 4.5-5.5 mm, circinnately incurved at apex, the stigmatic cavity latero-introrse; ovules 25-38. Pod ascending or commonly bent at base and so appearing pendulous, the linear piano-compressed body (1.5-)2-3 dm long, 1.2-1.5(-1.6) cm wide, cuneately contracted at base into a stout stipe 5-9 mm, coarsely bicarinate by the thick riblike sutures, the brown, stiffly coriaceous or subligneous, venulose valves alternately expressed and depressed over the seeds, the interseminal septa not elevated, the locules broadly elliptic 7-10 mm long; seeds very strongly compressed parallel to the valves, discoid, 6.5-8 x ±5.5-6 mm, the testa castaneous lustrous, the narrowly oblong-elliptic areole 3.2-4.5 x 0.9-1.2 mm. Collections: 57.
Distribution and Ecology - A tree of forest or forest margins at low elevations, native probably to Burma and Thailand, widely planted throughout the Tropics and locally naturalized, a common tree of parks and avenues, in the Old World employed as windbreak or coffee-shade, in the New mostly as an ornamental: s. peninsular Florida; Bermuda and Greater Antilles, where introduced in early XIX century; s. Mexico (Tabasco, Chiapas) s. through Central America to n. Colombia, n. Venezuela and s. Brazil (cities of Amazonia, Brasilia and environs, coastal Bahia, Guanabara, Sao Paulo); Hawaiian Is.
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Discussion
Fresh seeds of the Kassod Tree germinate readily, the tree itself grows rapidly and flowers both precociously and prodigally, and it is these virtues rather than any particular aesthetic merit which have favored its spread and propagation in the Neotropics. For unless carefully pruned the tree ages ungracefully, the flowers are not especially showy (notably less so than those of S. multijuga or S. macranthera, which have the same general habit and uses), and the dead inflorescences with their abundant pods that persist long on the branches give it after flowering an untidy or moribund appearance. In the Old World S. siamea is grown less for ornament than as a windbreak or shade-tree in orchards and door- yards, and its wood used both for fuel and for turnery, for which the hard heart- wood is preferred. De Wit (1955, p. 265) mentions minor medicinal and magic uses in Malaysia. The living wood is said to resist termites in Africa, but when dry becomes highly susceptible in the New World. The foliage, pods and seeds are fatally toxic to swine.
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Common Names
Kassod Tree, jahor , johor
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Distribution
Tabasco Mexico North America| Chiapas Mexico North America| Florida United States of America North America| Bermuda South America| Cuba South America| Cayman Islands South America| West Indies| Jamaica South America| Puerto Rico South America| Colombia South America| Venezuela South America| Brazil South America| Hawaii United States of America North America|