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

234 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN [VOL. 35
Pod dechned at random angles, often persisring through a fuU season on an­
norinous branchlets, the stipe 2-5 mm, the narrowly hnear body simply or sig­
moidaUy decurved (10-) 12-22 x 0.3-0.4(-0.45) cm, compressed-quadrangular,
carinate by the thick sutures and by a rib running the length of the valves a trifle
closer to the dorsal than to the ventral suture, the stiffly papery, densely rusty-
pUosulous or -strigulose valves scarcely raised over seeds but marked at the
interseminal septa by shaUow transverse sulci, these distant 4-7 mm; seeds ver-
ricaUy aligned along pod, in outhne oblong or obtusely rhombic (3-)3.3^.2 x
1.7-2.4 mm, the testa lustrous olivaceous or brown smooth, the oval or elliptic
areole 1-1.5 x 0.4-0.8 mm.—Collections: 49.—Fig. 9 (periolar nectary), 22 (pod).
Cerrado, usuaUy in red sandy soUs, becoming locaUy abundant in disturbed
environments, sometimes forming extensive thickets along roadsides,
(200-)400-1050 m, common and widespread over the Brazihan Planalto w. of Rio
S. Francisco, from the middle Tocanrins vaUey in Goias w. to the sources of Rio
Xingu in Mato Grosso, thence s. through Goias to the upper Paracatu and Pa-
ranaiba in w. Minas Gerais, and s.-w. through centr. and s. Mato Grosso just into
centr. Paraguay and s.-e. Bolivia; disjunct on Rio Mogi-gua9U in centr. Sao Paulo
(mun. Sao Carlos), and remotely so on savannas of upper Mazaruni River in
Guyana and along middle Orinoco River in Amazonas, Venezuela.—Fl. (I-)II-VI.
A handsome but rather coarse senna, which might be considered the prototype
of ser. Laxiflorae, notable for the dense, loosely pilose vesture of leaves and
flowers, for the characteristic gland at base of each pedicel, and for the narrow
compressed pod keeled along each valve by a prominent rib and divided into
seed-locules longer than their diameter. It is closely related to the coastal S.
australis and to S. cana, vicariant in the drier cerrado and caatinga country to
the northeast, which see for differential characterization.
As implied in the foregoing synonymy, we have drawn the description of S.
velutina so as to include Cassia dysophylla Benth. From the first C. dysophylla
has been thought to differ only in the narrow deciduous rather than fohaceous
and subpersistent stipules, but these, while striking in their extreme expressions,
which alone were known to Bentham, are now found to be highly variable. In
reality the stipules are never really setaceous from the base, as described for C.
dysophylla, but are always a httle dilated proximally even though not, at their
narrowest, auriculately amplexicaul. From this narrow type of blade we can now
trace an uninterrupted series increasing by increment on the side exterior to the
petiole, passing through a semicordate into a fully fohaceous type dilated and
pinnately veined (like leaflets) on both sides of the midrib. Broad amplexicaul
stipules of the velutina type are relatively rare within the whole range of the
species as here defined. They have been collected most frequently on the Xingii-
Araguaia divide in northeastern Mato Grosso but even here they do not wholly
replace the semicordate type, which is associated with precisely the same leaf,
flower and pod. Both sorts of stipule were collected at points 20-25 km south of
Xavanrina (Philcox & Fereira 3838; Hunt & Ramos 5986, both NY), and again
far to the east on Sa. Geral northeast of Formosa in Goias (Irwin et al. 15134,
15182, both NY), where narrow stipules appear dominant. Transitions between
semicordate and narrowly semi-lanceolate stipules are frequent (cf. Irwin 2530,
Mendes Magalhdes 18998, both NY, from between Uberlandia and Monte Alegre
in the Minas Triangulo).
The flowering plants coUected by Schomburgk (BM, K) in Guyana seem not
to differ in any way from some narrow-stipulate S. velutina from Goias. It is the
Cassia arowana Schomb., Reise Guiana, 1206, mentioned by Bentham (1871, p.
582) as a nomen nudum.