Chamaecrista serpens var. grandiflora (Benth.) H.S.Irwin & Barneby

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 2: 455-918.

Family

Caesalpiniaceae

Scientific Name

Chamaecrista serpens var. grandiflora (Benth.) H.S.Irwin & Barneby

Type

Lectoholotypus, Weddell 2286, from "rives de l’Araguay," P! presumed isotypi, Weddell s.n., G(3 sheets)!

Synonyms

Cassia serpens L., Cassia tenella Kunth, Chamaecrista tenella (Kunth) Pittier

Description

Variety Description - Habit, stature, foliage, pod of var. serpens, but flower larger, the cucullus (8—)9— 13(— 16) mm, the longer anthers up to 5-8 mm, the style (4—)5-6.5(-7) mm — Collections: 41. [Key: "Fl larger, the asymmetric petal 9-19(-20) mm, the longer anthers to 4-9.5 mm, the style (4-)4.5-10 mm; discontinuously dispersed from s. Arizona to n. Argentina. Lfts of larger lvs 3-7(-8) pairs; s. Mexico (Puebla, Oaxaca); Central America (Honduras and Nicaragua); South America (middle Orinoco valley to Argentina, localized and discontinuous). Lfts of relatively narrow outline, the wideset of a plant mostly less than 2.5 mm broad. Petiolar gland usually 1; either Mexico or S. America. Venulation of lfts scarcely prominulous; stipules less than 1.5 mm wide, not cordate at base; S. America, lowland."]

Distribution and Ecology - River banks, sandy floodplains, savanna (n.-ward) and campo (s.-ward), mostly below 600 m, known from 3 widely separated areas in S. America: banks of the Orinoco about the common boundaries of Apure, Amazonas, and Bolívar, Venezuela (to be expected in n.-e. Vichada, Colombia); Araguaia and Tocantins valleys in Pará and centr. Goiás, Brazil; middle and lower Paraguay and Paraná valleys in s.-w. Mato Grosso, Brazil, s.-centr. Paraguay and adjoining Argentina (Formosa; about the Misiones-Corrientes boundary); ?n.-centr. Bolivia (Mamore valley; cf. discussion infra).—Fl. at low latitudes nearly throughout the year, in Paraguay and Argentina mostly X-III, sometimes later.

Discussion

The three disjunct major populations which we refer to var. grandiflora are essentially alike in corolla-size, and differ only minutely in other characters. The plants of the Orinoco valley (C. tenella H.B.K.) tend to have, at maturity, very long stems, up to 5—10 dm, and relatively long petioles (2.5-4 mm) incurved- puberulent but lacking setae. In the context of copious material now available from the banks of the middle Orinoco the typus of C. tenella is peculiar only for its diminutive stature, the stems about 12 cm long from a knotty root-crown. It is evidently a depauperate individual, and led Bentham (1871, p. 571) to maintain the species in his ser. Paucijugae, next to C. schlimii, artificially separated from its real affinity within ser. Prostratae. The short-stipitate glands, now known to occur in typical C. serpens, may well have exerted an influence on the misinterpretation. The plants of Argentina and Paraguay are more compact, with stems 1-4 dm and short petioles (1.2-2.5, rarely 3 mm) setose as var. serpens. The two known collections from Goiás are intermediate in stature and petiole-length. North of Capricorn the leaflets are uniformly glabrous; in Argentina and Paraguay either glabrous or thinly setose, the latter prevailing in Argentina and the former around Asunción. A fragmentary specimen (O. Braun 2, NY) from the lower Mamore valley in dept. Beni, n.-centr. Bolivia, appears to represent a broad-leaflet form of var. grandiflora but lacks expanded flowers or fruits and is inadequate for analysis. The discontinuous range of var. grandiflora lies almost within that of var. serpens but they appear nowhere to overlap, the former indeed fitting neatly into gaps in the dispersal pattern of the latter. Perhaps var. grandiflora consists not of a phylogenetically pure strain but is a composite of parallel variants, at present morphologically inseparable, that have arisen independently from var. serpens and replace it locally.

Distribution

Apure Venezuela South America| Amazonas Venezuela South America| Bolívar Venezuela South America| Vichada Colombia South America| Pará Brazil South America| Goiás Brazil South America| Mato Grosso Brazil South America| Formosa Argentina South America| Corrientes Argentina South America| Misiones Argentina South America| Bolivia South America| Paraguay South America|