Cassiinae pt 1 NY-Botanical_gardens_Vol. 35_1 - Copy.pdf - Antbase

256 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN [VQL. 35
WhUe S. pentagonia becomes instanriy recognizable so soon as its curiously
winged ovary begins to expand, its smaUer-flowered forms are at anthesis scarcely
disringuishable from S. obtusifolia except by the longer (at least 1, not ±0.4-0.6
mm) beak of the three abaxial anthers. The hkeness is so faithful that there can
be htrie doubt that S. pentagonia originated by mutarion from the common sickle-
pod or an immediate ancestor. These related species were both first described by
contemporaries of Linnaeus, but whUe the former has long been recognized as
almost circumtropical in dispersal the latter, although similariy weedy in behavior,
has proved singularly rare and local, the few known populations being loosely
concentrated bicentricaUy in extra-Amazonian south Brazil and in northern Cen­
tral America and adjoining Mexico. The plants of the northern hemisphere are
aU, so far as known, relarively small-flowered, as are those of BrazU southward
along the S. Francisco vaUey from western Bahia to eastern Sao Paulo. From a
StiU meager sample it appears that the anther-beaks of the Brazilian plants are
shorter than those of North American ones, about 1-1.5, not 1.8-2 mm long, but
the difference, if real, is inconsiderable, being unsupported by other characters.
In the central BrazUian highlands the species is represented by a large-flowered
race with extraordinarily long anther-beaks, described below as var. valens. Dif­
ficulty must be expected in separating fruiting material of var. valens from var.
pentagonia, which are virtually identical in vegetative characters and in the pod;
in fact a specimen from southern Goias (Goias Velho, BurcheU 7062, LE, NY)
already presents this problem. The range of var. valens overlaps that of the
similarly large-flowered S. mucronifera, which may be separated without difficulty
by the greatly elongate and very narrow wingless pod and at anthesis by
the pubescent, emphaticaUy venulose leaflets.
Key to Varieties of S. pentagonia
1. Fls relatively small, the longest sepal 7-9 mm, the longest petal 11-15 mm; style 3^ mm;
body of 3 abaxial anthers 3-4 mm, their beak 1-2 mm; dispersal bicentric: s. Mexico to
Honduras; s.-e. Brazil. 70a. var. pentagonia (p. 256).
1. Fls larger, the longest sepal 13-15 mm, the longest petal 21-30 mm; style 6.5-8 mm; body
of 3 abaxial anthers 9-10 mm, their beak 4-5 mm; Brazilian Planalto (s. Maranhao, e.-centr.
Goias and w. Bahia). 70b. var. valens (p. 257).
70a. Senna pentagonia (P. MiUer) Irwin & Barneby var. pentagonia. Cassia pentagonia
P. Miller, 1768, I.e., sens. str.—''Senna spuria . . . siliqua
pentagona alata. Houston MSS . . . sent me from Campeachy by the
late Dr. Houston."—Holotypus, so ticketed in Houston's hand and
annotated by Solander, BM! = BH Neg. 5164 = NY Neg. 759. The
pod had been illustrated earher by P. MUler, Fig. t. 82, flg. c. 1760,
but there mistakenly associated with a plant of C. bicapsularis. Er­
roneously equated by Martyn, Gard. Diet. ed. 9, and by Britton &
Rose, 1930, p. 242 (sub Emelista) with C. tora; restored by Bentham,
1870, p. 114, t. 34, fig. II; 1871, p. 535.
Fruiting pedicels 14-22 mm; otherwise as given in key.—Collections: 13.
Disturbed thickets, weedy grassland, roadsides, ditches and lake shores, not
known to occur on limestone and certainly not confined to calcareous soUs, most­
ly below 750 but ascending in Chiapas to 1270, in Honduras to 1200 m, rare and
scatterd: s. Mexico (Gulf slope in Chiapas and Campeche; Pacific slope in w.
Guerrero), and Honduras (Morazan); s.-e. BrazU (w. Bahia to s.-centr. and s.-e.
Minas Gerais and e. S. Paulo).—Fl. in N. America IX-X, in BrazU III-IV.