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

428 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN [VOL. 35
primitive multiflorous raceme. Our six varieties of S. hirsuta are for the most
part genuinely ahopatric and vicariant. The species as a whole is, hke C. occi­
dentalis, prevailingly weedy even where native, and we suspect that random
records of a variety from phytogeographically improbable stations and, indeed,
some continuous or semi-continuous extensions of range are due to human in­
terference. It is generally conceded that S. hirsuta is an American weed in Africa
and Southeast Asia, but it is widespread there and has proved its abihty to spread
over great distances in ruderal habitats. Thus we have no real gauge by which to
assess the extent to which any form of S. hirsuta is genuinely autochthonous
except as a particular phase of it conforms to known patterns of geographical
dispersal.
The varieties of S. hirsuta are serially ordered below to conform whh the
hypothesis that obsolescent vesture, coarse hirsute vesture, an abbreviated, few-
flowered, pseudo-umbellate raceme and a condensed pod with densely crowded
seeds are derived or specialized features, and that the more primitive forms of
the species are those found today in the Paraguai-Uruguai basin, near or astride
the Tropic of Capricorn between southern Bohvia and Rio Grande do Sul in
Brazil. It follows that var. streptocarpa, which closely resembles the vicariant
S. neglecta, is placed first and var. hirsuta last. Generally speaking the varieUes
with more numerous derived features are dispersed correspondingly further north
or northwest from the presumed focus of speciation for the section in southern
Brazil.
Key to the Varieties of S. hirsuta
Lfts pubescent on both faces and cili(ol)ate, the longer hairs 0.4-2.8 mm.
2. Vesture of lfts strigulose or softly pilosulous, the hairs when loose commonly incumbent
or incurved, less often straight and spreading, in any case not highly lustrous nor more
than 0.4-0.7 mm long; S. America in lat. 17-30°S.
3. Pod both arched outward and spirally twisted, commonly sigmoid when flattened in
press; racemes mostly 8-35-fld; fls small, the longer inner sepals 5-7 mm, the longest
petal 8-13.5 mm; n.-e. Argentina (Misiones) and adjoining Brazil (Rio Grande do Sul).
138a. var. streptocarpa (p. 429).
3. Pod simply arched outward, not twisted; racemes in Bolivia and Paraguay 2-8-, in
Argentina and e. Brazil (centr. Minas Gerais) to 6-14-fld; fls larger, the longer inner
sepals 7-10 mm, the longest petal 12-16 mm; s.-centr. Bolivia and n.-w. Argentina
(Salta, Tucuman, Santiago del Estero) to Paraguay, disjunct in s.-e. Brazil (Minas
Gerais); adventive in Philippine Is.
4. Pod 15-25 X 0.3-0.5(-0.55) cm; ovules 66-82; range as just given except Brazil.
138b. var. puberula (p. 429).
4. Pod 15 X 0.7 cm; ovules ±54; centr. Minas Gerais, apparently very local.
138c. var. acuminata (p. 431).
2. Vesture of lfts hirsute, the hairs straight, spreading or ascending, highly lustrous, the
longest 0.6-2.8 mm; equatorial S. America n.-w. and n. to tropical Mexico and W. Indies,
s. infrequently and interruptedly in Brazil and Bolivia to ±17°S.
5. Pod slender, usually elongate and curved out- or both out- and downward,
(14-)15-27 X 0.25-0.45(-0.5) cm; Mexico and w. Cuba s.-e. through Central America
to n. Colombia, thence s. along the Andes to n.-w. Bolivia, in S. America essentially
cordilleran. 138f. var. hirta (p. 433).
5. Pod stouter, shorter and straight, 11-15 x (0.4-)0.45-0.65 cm; n. S. America from
Colombia to the Guianas, s.-e. in Brazil to Maranhao and (disjuncdy) s.-centr. Goias,
n. to the Greater and Lesser Antilles; widespread as a weed in Old World Tropics.
138g. var. hirsuta (p. 434).
Lfts on upper face glabrous or very minutely puberulent, elsewhere thinly puberulent or
strigulose, the longest hairs 0.2-0.4 mm; either s.-e. Brazil or Mexico and s.-w. United
States.
6. Venation of both faces of lfts finely prominulous, the blades openly reticulate; s.-e. Brazil
(local in Rio de Janeiro and adjoining Minas Gerais). 138d. var. leptocarpa (p. 431).