Cassia amphibola H.S.Irwin & Barneby

Authors

Howard S. Irwin, Rupert C. Barneby

Authority

Irwin, Howard S. & Barneby, Rupert C. 1978. Monographic studies in Cassia (Leguminosae, Caesalpinioideae). III. Sections Absus and Grimaldia. Mem. New York Bot. Gard. 30: 1-300.

Family

Caesalpiniaceae

Scientific Name

Cassia amphibola H.S.Irwin & Barneby

Type

Holotypus, LE (2 sheets) = NY Neg. 9180.

Description

Latin Diagnosis - Cassia amphibola Irwin & Barneby, sp. nov., C. setosae Vog. pube viscido-setosa ac foliolorum forma arete comparandae forsan proxime affinis sed ab ea (ut ab aliis Setosis omnibus) foliolis 3-5 (nec 1-2)-jugis margine planis facie inferiori reticulatis vix alveolatis necnon inflorescentia parum exserta basi foliata e racemis paucifloris composita facillime distinguenda.

Species Description - Erect, amply leafy shrubs 9-12 dm, finely villosulous throughout with short weak, erectly spreading hairs, and the stems, lf-stalks and axes of inflorescence in addition densely hispid with bulbous-based viscid setae up to ± 1-1.5 mm, the foliage bicolored, the lfts above brownish-olivaceous sublustrous and villosulous, beneath paler and at once villosulous and setulose, the complex paniculate inflorescence leafy proximally and shortly exserted distally. Stipules erect subulate 1.5-2.5 mm, early dry and deciduous. Lvs ascending, the principal ones 7-12.5 cm, coarsely petiolate; pulvinus moderately dilated but little differentiated in texture 2-3 mm; petiole 2-4 cm, subterete, at middle 0.7-1.2 mm diam, the ventral sulcus very narrow, almost closed; lfts 3-5, mostly 4 pairs, ascending from rachis face upward, on fusiform-cylindroid setulose pulvinule 1.5-2 mm, accrescent distally, the chartaceous blades elliptic or broadly lance-elliptic, obtuse apiculate, 12-48 x (7-)9-20 mm, at asymmetric base cordate on proximal and broadly cuneate to rounded on distal side, the setulose entire margins plane or almost so, the subcentric midrib with 7-10 pairs of major incurved-ascending secondary veins above immersed or faintly impressed, beneath prominulous discolored, the tertiary and reticulate venulation finely prominulous only beneath, the ultimate areoles flat, not alveolately recessed, up to ± 1 mm diam. Inflorescence a complex panicle of short, loosely 5-12-fld racemes, the lower ones, as also sometimes their first 1-2 fls, leafy-bracteate, the one expanded fl raised to or beyond level of the horizontally spreading buds; bracts narrowly lance-subulate 2-3.5 mm, tardily deciduous; fertile pedicels 18-23 mm, bracteolate 2-3 mm below calyx; bracteoles resembling bracts, slightly smaller, persistent; buds ovoid acute, densely villosulous and setulose; sepals lance-elliptic, 10-11 mm, when fresh probably reddish; petals presumably yellow, 1 adaxial obovate-flabellate nearly 16 mm, the 3 other plane ones shorter and proportionately narrower ± 10—12 mm, the cucullus about as long, dimidiate, coiled; anther-sacs black when dry, densely ciIiolate along sutures, the connective produced as a deltate point between the terminal apertures; ovary densely pilosulous; ovules ±8.

Discussion

A striking plant of ambiguous affinity, which we reluctantly refer to ser. Setosae because of a general similarity in habit, in coarsely and densely viscid-hispid stems, and in general appearance of the foliage, to C. setosa var. setosa. From this it is easily distinguished by the 3-5 (not 2) pairs of leaflets which differ in details of the plane (not revolute) margins and finely reticulate (but not intricately alveolate) lower face; and further by the relatively compact, little exserted and proximally leafy panicle of few-flowered racemes. Plane leaflet margins are known elsewhere in ser. Setosae only in the rare and distantly allopatric C. ochrosperma, which is habitally very different in its few-leaved stem, glabrous foliage, and long terminal raceme of flowers. An inflorescence similar to that of C. amphibola is encountered in C. orenocensis, but combined with exactly two pairs of dorsally alveolate leaflets and abbreviated petioles. Other possible close kindred to C. amphibola are ser. Nigricantes, similar in number and sometimes in venulation of leaflets, but these always revolute-margined and the stems never coarsely setose. On the other hand the horizontal attitude assumed by the flower buds immediately before anthesis and also the (poorly known) form and coloration of the expanded perianth recall C. (ser. Catharticae) cathartica, even though the racemose-paniculate, not axillary arrangement of the pedicels and the few pairs of large leaflets are incompatible with that. It occurs to us, however, that C. cathartica and C. setosa, both of which are found in northern Sao Paulo, could contribute jointly to a hybrid derivative almost all gross morphological features of C. amphibola, the armament of setae being that of C. setosa, the flower that of C. cathartica, while the inflorescence is of intermediate type just as the leaflets are of intermediate number and venulation. Speculation in this direction, however, is hardly profitable until more collections and field observations can be made.

Distribution

São Paulo Brazil South America| Brazil South America|