Senna cajamarcae H.S.Irwin & Barneby
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Authors
Howard S. Irwin, Rupert C. Barneby
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Authority
Irwin, Howard S. & Barneby, Rupert C. 1982. The American Cassiinae. A synoptical revision of Leguminosae tribe Cassieae subtrib Cassiinae in the New World. Mem. New York Bot. Gard. 35, part 1: 1-454.
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Family
Caesalpiniaceae
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Scientific Name
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Type
Holotypus, NY.
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Synonyms
Senna mandonii (Benth.) H.S.Irwin & Barneby, Cassia pendula var. bracteata Lass.
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Description
Species Description - Shrubs and treelets ±1.5-3 m, with pallid hornotinous and fuscous or almost black older branchlets, appearing glabrous but in fact residually puberulent on lf- stalk, pulvinule and axis of inflorescence (or some of these) and the lfts minutely sparsely ciliolate, the foliage strongly bicolored, the firmly chartaceous lfts above dark dull green with pallid line along midrib, beneath pallid-glaucescent overall, the early racemes lateral and scarcely as long as subtending lf, some later ones forming a shortly exserted panicle. Stipules ascending, firmly herbaceous oblanceolate or elliptic-oblanceolate 4-9 x 1.5-3 mm, the blade replicate on itself, persistent into and commonly past maturity of associated lf. Lvs mostly 6-14 cm, some smaller ones high in the inflorescence not further described; petiole including little differentiated pulvinus 1.5-3 cm, at middle 0.6-1 mm diam, subterete, the ventral sulcus narrow or obscure, becoming more evident on rachis, this 2-6.5 cm, its longer interfoliolar segments (8-)10-17 mm; glands (caveat: much eaten) between proximal and commonly between all pairs but the distal one, subsessile ovoid-apiculate, the lowest one in profile 0.9-1.7 x 0.45-0.7 mm, the distal ones often smaller; pulvinules 1.2-2 mm; lfts (3-)4-6 pairs, moderately accrescent distally, the distal pair elliptic or lance-elliptic obtuse or minutely emarginate (19-)23-46 x (7-)8-14 mm, 2.6-3.3 times as long as wide, at base asymmetrically rounded or subcordate, the (mature) margin plane, the midrib immersed above, stoutly cariniform beneath, the (7-)8-11 pairs of very slender camptodrome secondary veins barely perceptible on either face or faintly raised beneath, tertiary venulation 0. Racemes 7-20-fld, the 1-2 simultaneously expanded fls raised ± to level of ascending, obliquely obovoid buds, the axis with peduncle together (3.5-)4-10.5 cm; bracts resembling stipules in texture, green or eventually brunnescent, ovate-acuminate or lanceolate 2-5 x 1.4-2.4 mm, sometimes revolute but sometimes plane, persistent into or sometimes beyond anthesis of subtended fl; pedicels 10-21 mm; sepals submembranous brown or fuscous, the inner ones narrowly pallid-margined, all ovate or obovate obtuse, moderately graduated, the smallest outer one 4-5.5 the largest inner one 6-10 mm; corolla zygomorphic, the glabrous short-clawed petals yellow drying brownish-yellow brown-veined, the flabellate- obovate vexillar one 8.5-12 mm, the rest nearly as long; androecium glabrous, the blade of 3 staminodes 1.2-1.6 x 0.8-1.5 mm, the filaments of 4 median stamens 1.1-2.5 mm, of the centric abaxial one 2-2.5 mm, of the 2 long latero-abaxial ones 5.5-8.5 mm, the anthers of 4 median stamens narrowly flask-shaped 3-3.9 x 0.9-1 mm, of the sterile abaxial one 2.5-4.5 x 0.5-0.7 mm, of the 2 long ones lunately lanceolate in profile 5.5-8.5 x 1.1-1.5 mm, the obscurely differentiated, horizontally truncate beak of these 0.4-0.6 x 0.6-0.7 mm, its orifice divided by slender septum into 2 pores; ovary thinly strigulose-pilosulous; style glabrous linear-attenuate 3.5-4.9 mm, at gently incurved apex 0.2-0.3 mm diam; ovules 30-36. Pod (little known) obliquely ascending or declined, the stipe 5-6 mm, the fully fertile (often in fact imperfect and variously distorted or malformed) body linear subterete ±5-6.5 x 0.7-1.2 ("-1.5") cm, the valves firmly chartaceous smooth, brown or castaneous, the seed-locules ±2-2.5 mm long, as wide as the pod’s cavity, apparently thinly pulpy within; seeds transverse, turned with broader faces to the septa, plumply compressed obovoid 4.5-5.5 ("-6.5") x 2.5-3.5("-4") mm, the testa brown or atrocastaneous lustrous smooth or remotely pitted, ex-areolate.—Collections: 8.—Fig. 27.
Distribution and Ecology - Shrub-thickets and disturbed brush-woodland in the monte or ceja de montana formations, 2200-2850 m, local on and along the Andean divide in s. Ecuador (Loja) and n. Peru (Cajamarca, prov. Chota and Cajamarca), lat. 4°-7°20'S; and distantly disjunct, in unrecorded habitats at 1200-1800 m, on w. slope of Cerros Volcan and Horqueta in n.-w. Chiriquf, Panama.—Fl. VII-XII, II—III, perhaps throughout the year.
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Discussion
Senna cajamarcae closely resembles S. mandoni in habit of growth and in the strongly bicolored, dorsally glaucescent, almost veinless leaflets, but differs in the more persistent, firmly herbaceous stipules and floral bracts, a less strongly incurved style, and especially in the subterete pod that contains seeds turned with broader faces to the septa and not to the valves. The herbaceous replicate stipules might suggest relationship to S. versicolor, certainly almost and perhaps actually sympatric in Cajamarca, but this is obviously different at anthesis in its more numerous (8-13, not 3-6) pairs of leaflets and later on in the piano-compressed pod and the areole on the seed-faces. We see no close connection with S. pendula, of which the stipules are membranous and caducous. The pod of S. cajamarcae appears quite variable in girth, and Lasseigne describes the seeds as biseriate, although they are certainly uniseriate in the material studied by us. The typus of Cassia pendula bracteata, known to us only through a photograph, has fully ripe, dehisced pods at least 12 mm diam, whereas in other specimens from the same general vicinity (e.g. Reichlen 45, P) and in our one record from Ecuador (Wiggins 10949, NY) it is only 7-8 mm diam. The plants are identical in other respects and surely conspecific in a broad sense; an enquiry on the spot will settle whether the variation is random or reflects a genuinely established racial dichotomy. Our one Panamanian record with flowers (Maurice 849, US) has slightly larger anthers than any yet recorded for Andean S. cajamarcae, but is closely similar in all other details ascertainable from a specimen at anthesis. Pods from the same region (Tyson 5711; Correa 1315, both MO) confirm the identity.
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Distribution
Loja Ecuador South America| Cajamarca Peru South America| Chiriquí Panamá Central America|