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

344 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN [vOL. 35
7.5-10.5 mm) petals; and instantly separable when ripe fruh is present by the
areolate seed-faces.
llOf. Senna birostris (Vogel) Irwin & Barneby var. birostris. Cassia birostris
Dombey ex Vogel, 1837, I.e., sens. str.—"Hbt. in Chih: Dombey leg.
(. . . Hrb. Kth. . . .)."—Holotypus, fB = F Neg. 1657; neoholotypus,
coUected by Dombey at Chinchina, prov. Huarochiri, dept. Lima,
Peru, P! isotypus, hb. Pavon. s.n., MA! presumed isotypus, Dombey
S36, G!—Chamaefistula birostris Dombey ex Macbride, Field Mus.
Bot. 13, part 3(1): 158, pro syn. 1943.
Cassia birostris sensu Bentham, 1871, p. 540; Macbride, I.e., exclus. pl. amazonica.
Bushy shrubs at anthesis 4-15 dm, the young stems, lf-stalks and inflorescence
thinly strigulose-pUosulous with pale straight or incurved hairs up to 0.2-0.7 mm,
the duh ohvaceous, relatively thin-textured lfts glabrous above, either glabrous
or remotely pUosulous beneath, the racemes either lateral or corymbose-paniculate
but all leafy-bracteate, either early elongating, the open fls then standing
well below the racemose buds, or compactly pseudo-corymbose; stipules narrowly
hnear-attenuate 4-11 x 0.3-0.7 mm; lvs 7-15(-21) cm; petiolar gland either
between or shortly above proximal pair; lfts 7-12 pairs, on pulvinules 0.7-1.4
mm, ovate- or elliptic-oblong and obtuse to deltately subacute or broadly ovateorobovate-emarginate,
the longest ll-24(-32) x 5-ll(-12)mm, 1.5-2.7(-3) times
as long as wide, veinless above, the dorsally prominent midrib giving rise to
4-6(-7) pairs of fine, immersed and discolored or, toward the pulvinule, sub­
prominulous secondary veins; racemes (5-)7-l5(-18)-fld; sepals glabrous or almost
so, little graduated, the outer (4.5-)5-7 mm, the inner 6.5-8.5 mm; longer
petals 9-13 mm; filaments of 2 latero-abaxial stamens 6-11 mm, ofthe centric
abaxial one 3-7 mm, the anthers of all 3 subequal 5-7.8 x (1-) 1.3-1.8 mm; ovary
pUosulous; style 1.4-2.2 mm; ovules ±12-14; stipe of pod 4.5-7.5 mm, the body
±6-8 X 1-1.2 cm.—Collections: 17.
Stony clay hills and quebradas in the loma formation, 370-2000(-2250) m, in­
terruptedly frequent along the Pacific slope ofthe Peruvian Andes from s. Ancash
(Huarmey) to w. Arequipa (CaravelO, lat. ±10°-16°S.—Fl. irregularly through
the year.
In this variety the androecium of S. birostris attains its greatest asymmetry,
the long pair of abaxial stamens protruding their relatively massive anthers weU
beyond the petals, an arresting feature of the flower that must have suggested the
epithet. These long stamens are, however, only on the average slightly longer
than those of var. arequipensis, which see for comment, and var. helveola, which
replaces var. birostris at slightly greater elevations on the Andean plateau to the
east and northeast. The latter differs from var. birostris principahy in the more
abundant, often yehowish pubescence of fohage and inflorescence and in the
strongly graduated, dorsally pUosulous sepals. The pod of none of these varieties
is weh known, but the few examples we have appear essentiaUy similar.
Many populations of var. birostris differ from other races of the species in the
early elongating raceme axis, which carries the developing flower buds weU beyond
the level of the open flowers; others, however, have more condensed cor­
ymbiform racemes normal for the species. The different types of inflorescence
are not related to elevation of habitat, for both are known from the foothiUs below
750 m and from near the altitudinal hmit of 1800-2000 meters. Dombey's original
Cassia birostris was of the condensed, apparently less common type.