Senna silvestris subsp. silvestris var. silvestris

Authors

Howard S. Irwin, Rupert C. Barneby

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.

Discussion

3a. Senna silvestris (Vellozo) Irwin & Barneby subsp. silvestris var. silvestris. Cassia silvestris Vellozo, 1825, l.c. & Icones 4: t. 78. 1835.—"Habitat silvis maritimis Reg. Praedii S. Crucis [s.-w. Rio de Janeiro]."—Holotypus, the cited plate!

Cassia lucens Vogel, Syn. Gen. Cass. 46 & Linnaea 11: 687, descr. ampliat. 1837.—"In Brasilia: Sellow leg."—Holotypus, presumably †B; neoholotypus, former isotypus, K! = NY Neg. 1469.

Cassia racemosa var. tenuifolia Huber, Bol. Mus. Goeldi 4: 564. 1906.—"([J. Huber] 1470) . . . PERU. Loreto: Ucayali: ‘Quebrada Grande’ de Canchahuaya, 13.XI. 1938."—Holotypus, presumably MG, not seen.

Cassia racemosa sensu Bentham, 1870, p. 126; 1871, p. 549; auct. plur. recentior., non P. Miller, 1768.

Cassia lucens sensu Amshoff, On South American Papillionaceae 23. 1939.

Arborescent on riverbanks and in forest, then 5-20(-30) m tall, sometimes arborescent and distally sarmentose, in capoeira, cerrado and savanna flowering precociously as coarse suffrutices or soft-woody shrubs (2-)3-6 m, the lfts glabrous above, pubescent beneath either overall or only along principal veins with straight appressed or ascending hairs up to (0.15-)0.2-0.6 mm, the reticulation of upper face of lfts either sharply prominulous or immersed, that lower lace prominulous, but the areoles plane and shallow; lvs mostly (2.5-)3-6 dm, shorter only at or near base of panicle; lfts (6-)7-11(-13) pairs, the larger ovate- or lance- acuminate from rounded base, (6.5-)7-13(-15.5) x 2-4(-4.3) cm; flowers variable in size, the long inner sepals mostly 7.5-11 (-13), in Peruvian and adjacent Brazilian Amazonia only 6.5-7.5 mm, the pure yellow petals (9 ) 13 21 ( 23) mm, long anthers (5-)6-9(-11) mm; ovary either glabrous, or ciliolate along sutures or pi- losulous overall; ovules 36-60; body of pod (12-)15-24(-27) x 1.6-2.8(-3.3) cm, the locules 1-seriate or, in very wide pods, a few of them laterally displaced and randomly 2-seriate.—Collections: 192.—Fig. 10 (androecium), 13 (pod + seed), both under synonym lucens.

Forest margins, especially along riverbanks and shores and in gallery-savanna ecotone, both in varzea and terra firme, in disturbed woodlands, and savanna thickets, becoming a vigorous pioneer in capoeira, mostly between 15 and 500 m but ascending to 1200 m on Guayana Highland (Sa. Tepequem), to 750 m along inter-Andean valleys in Peru, to 900 m in the Bolivian Yungas, and to 1500 m in s. Sa. do Espinhaço in Minas Gerais, bicentric in dispersal: widespread and locally common over the Guayana Highland and whole Amazonian Hylaea from middle Orinoco valley s. to lat. 17°S in Bolivia and 14°S in Mato Grosso, w. in Peru to the middle Maranon, upper Huallaga and Middle Ucayali valleys, e. to the interior of the Guianas and in Brazil to the middle Tocantins valley and n. Maranhao, n. in Venezuela to Maracaibo Basin; disjunct on the Atlantic slope and coastal forest of s.-e. Brazil: s. Bahia (very local near Vitoria da Conquista), highland s.-e. Minas Gerais (Sa. da Caraga, Caiete and vicinity), and along the foothills of the Coast Range from s.-w. Rio de Janeiro to Santa Catarina.—Fl. in the Hylaea year around, most prolifically VIII-IV, in s.-e. Brazil XII-III.—Brujillo (Venezuela); katawerewere (Guyana); parica, mucurao (Para); yacucaspi, quillu-sisa, tampush, shanshan (Peru); mamuri (Bolivia). Wood hard, used for gunstocks in Maranhao.

The most widespread variety of its species, var. silvestris is predominantly a senna of forest margins in the Hylaea, from which it has radiated west into the Andean foothills and south into the cooler wet forest of Atlantic Brazil, becoming a composite of minutely different genetic races. Our attempts to extricate these in the form of useful and meaningful taxonomic units have not succeeded, the variable characters of vesture, flower-size and number of leaflets being poorly correlated and subject to individual as well as racial variation. The most noteworthy examples of the latter are 1) a small-flowered type dominant on the upper forks of the Amazon in Peru and adjacent Brazil, the flower at its smallest (long sepals 6.5-7.5 mm, long petals 9-12.5 mm, with proportionately diminished androecium) resembling that of Cuban S. gundlachii (=var. tenuifolia Huber, cited in the synonymy) and 2) sympatric with normal Hylaean var. silvestris on the upper Madeira and its tributaries in Rondonia and adjoining states a plant different in having relatively few (5-8) and ample pairs of leaflets combined often but inconsistently with a narrow pod (±10-15 mm wide). This narrower pod resembles that of subsp, bifaria var. velutina, also found near the belt of transition between the Planalto and the Amazon forest, but its foliage is that of subsp. silvestris, sometimes approaching with uncomfortable closeness that of var. sap- indifolia. An exceptionally wide pod (27-33 mm) occurs at random points in the Amazon Basin and on the Guayana Highland. In it some seeds are commonly displaced from vertical alignment down the middle of the pod, but the seeds are never sorted into two regularly alternating rows as in subsp, bifaria var. bifaria. Contrary to expectations, the populations native to mountainous Minas Gerais and to the coast ranges of south-eastern Brazil, far distant from the variety’s main range, seem to have acquired no distinctive qualities. Probably it was in this region that Sello collected the typus of Cassia lucens, which much resembles some modern collections from Sa. de Caraga and Caiete.

Identification of Cassia silvestris Vell., in which we differ from all antecedents, depends on interpretation of the protologue, for no specimen survives. Two elements of the protologue are, in our opinion, crucial and decisive: the type-locality at the imperial fazenda of Sta. Cruz on the coastal plain to the west of Rio de Janeiro city; and the figure of the pod, so drawn as to show the inner face of the valves with a single row of locules. Bentham, placing greater emphasis than seems justified in our present state of knowledge on shape of the leaflets, which are shown distinctly even though very shallowly cordate at base in Vellozo’s plate, identified C. silvestris with what is here called var. bifaria, the common planaltine plant which is not known to cross Sa. da Mantiqueira and differs from the coastal one in its broad, thick-textured, coarsely veiny pod enclosing a double row of seeds. From the plate alone, C. silvestris might be our var. unifaria, or the C. lucens of Vogel and modern authors. But only the last of these is found today on the Atlantic coastal plain. Bentham’s use for C. lucens of the name C. racemosa Mill, has rightly been challenged by Amshoff (1939, l.c.), who examined the typus of the latter at the British Museum but was unable to identify it other than negatively. The name C. racemosa is taken up in this revision for the Mexican and Cuban C. ekmaniana Urban.