Senna macranthera (DC. ex Collad.) 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
Typus infra sub var. macranthera indicatur.
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Synonyms
Cassia macranthera DC. ex Collad.
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Description
Species Description - Weak leaning or sarmentose, or more often erect and bushy shrubs or treelets at anthesis 1-3 m and slender trees of rapid growth reaching 3-9 mm with trunk 6-15 cm diam, the terete or low-ribbed branchlets like the bicolored or subconcolorous foliage variably pilosulous or strigulose with straight spreading, forwardly incurved, or narrowly ascending to subappressed, or truly appressed hairs up to 0.2-0.8 mm, the lfts pubescent beneath even if only thinly so, commonly on both faces, exceptionally subglabrous, the blades chartaceous, either olivaceous or brownish-olivaceous on both faces or paler beneath, sometimes papillate above, the inflorescence usually paniculate and exserted but either fully elevated above developed lvs or the lower racemes subtended by reduced lvs, the distal ones often by bladeless petioles. Stipules early dry, caducous from a slightly elevated scar before or with full expansion of associated lf, sometimes persistent into maturity of lf but then deciduous, linear-lanceolate to setiform 3-16 x 0.25-0.6 mm. Lvs below inflorescence 2-26 cm; petiole including firm, sometimes moderately dilated pulvinus 6-55 mm, at middle 0.4-1.8 mm diam, low-carinate dorsally and laterally subterete, shallowly (sometimes obscurely) open-sulcate ventrally, as long or commonly longer than rachis; rachis (1.5-)2-44 mm; gland between proximal pair of lfts sessile or shortly stipitate varying from depressed-pyramidal to ovoid-acute or -obtuse or clavi- or fusiform 1.2-4 x 0.3-1.7 mm, a second similar gland sometimes present at tip of lf-stalk, inserted behind the distal pair of pulvinules close next to the seta (or its scar, when fallen); pulvinules (0.8-) 1.2-5 mm; distal pair of lfts obliquely lance-elliptic to ovate or obovate, varying from short-acuminate obtuse to deltately acute (1.2-) 1.8-16 x (0.7-)0.8-6(-6.5) cm, 1.8-3.5(-4.5) times as long as wide, at asymmetric base cordate or rounded or broadly cuneate on proximal side, cuneate on distal one, the margin re volute, the straight or gently incurved midrib with 6-12(-13) pairs of major camptodrome and few weak or many almost as strong intercalary secondary veins either prominulous or immersed above, sharply prominent beneath, the connecting venules and ultimate reticulation variably defined down to larger areoles ±1-3 mm diam. Peduncles together with raceme axis 2-7.5(-10) cm, the latter 3-14(-17)-fld; bracts lanceolate, triangular, lance-ovate, or elliptic-oblanceolate 1.3-4 mm, caducous with first elongation of young pedicel or rarely persisting into anthesis; buds globose, puberulent or pilosolus; sepals either firm or submembranous, often yellowish or pallid or pallid-edged, strongly graduated, in outline broadly obovate- suborbicular to elliptic-oblanceolate, the largest of the inner ones 4-14.5 x 1.8-8 mm; petals puberulent dorsally especially along veins, homomorphic except for the often slightly wider adaxial one and for one abaxial slightly more oblique and nidulating the long stamens, all contracted into a slender claw 2-4(-5) mm, the blades varying from broadly obovate to oblong-oblanceolate, all obtuse, the longest (2-)2.5-4.5(-5) cm; filaments either glabrous or puberulent, those of 4 median stamens 1.5-3.5 mm, those of 3 abaxial ones (3-)4-9 mm, the anthers glabrous, puberulent in the grooves or thinly short-pilosulous, those of 4 median stamens slightly incurved 4-10 mm, with divaricate beak 0.4-0.7 mm, those of 3 abaxial ones more strongly incurved (6.5-)7.5-14.5 mm with porrect beak 0.8-2 mm; ovary densely pilosulous; style 1.5-5 mm, little dilated at apex, 0.55-0.8(-1) mm diam just below the incurved stigma, the cavity 0.2-0.6 mm diam; ovules 76-208. Pod pendulous or (when short) irregularly spreading, the stipe ±4-9 mm, the subcylindroid body straight or sinous 6-26 x 0.6-1.4 cm, the green valves becoming lustrously castaneous or blackish and glabrate, early corrugated by expression of the valves over the biseriate seeds, tardily dehiscent through the ventral suture and thus exposing the seeds embedded in foetid pulp; seeds turned broadside to the septa, compressed-pyriform 2.4-5.3 mm, the testa lustrous castaneous or mahogany-brown, cross-crackled, exareolate.
Variety Key - Key to the Varieties of S. macranthera 1. Plants of Atlantic and planaltine Brazil (Piaui and Ceara to s. Goias and Sao Paulo). Lvs variable in size; pod variable in length and diam but short (11 cm or less) only n.-ward from centr. Minas Gerais and Bahia. 2. Calyx relatively small, the largest inner sepal 3.5-7(-9) x 1.8-4(-5.5) mm, if over 4 mm wide less than 7 mm long. 3. Lfts strigulose with appressed hairs, often beneath only, the blades mostly elliptic. Arborescent when mature; larger lfts 6-16 cm. Ovules 154-192. 42a. var. macranthera (p. 183). 3. Lfts densely softly pilosulous with spreading-incumbent hairs, either on both faces or beneath only. Stature and lfts diverse. 4. Distal lfts of larger lvs 6-16 cm; arborescent when mature; pod 12-36 cm, (120-)140-208-ovulate. 42b. var. nervosa (p. 184). 4. Distal lfts of larger lvs 2-6(-7) cm; shrubs to ±3(-4) m; pod 7-10 cm, 112-140-ovulate. 42c. var. micans (p. 185). 2. Calyx relatively ample, the largest inner sepal 7-14 x 4.5-8 mm; shrubs 1.5-3 m. Ovules 92-144. 5. Distal lfts of larger lvs (5.5-)6-11 x 1.6-3.8 cm, strigulose beneath; pod 12-20 cm. 42d. var. striata (p. 185). 5. Distal lfts of larger lvs 2-6(-6.5) x 0.8-2.5 cm, pilosulous beneath; pod 7-10 cm.
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Discussion
In course of analyzing the very extensive material of ser. Bacillares ** Speciosae Benth. now at hand for study, our concept of S. macranthera has become substantially more comprehensive than that of the recent past, absorbing the Brazilian Cassia speciosa and C. pudibunda of Bentham’s revision, the Venezuelan Chamaefistula quadrifoliolata Pitt., and related entities from Andean Peru and Colombia of which specimens have lain unidentified or unappreciated in herbaria. Bentham’s definitions, based of course on a relatively poor and fortuitously selected sample, have become unworkable. Ideally his C. speciosa and C. pudibunda should be alike in pubescence but should differ in size of leaves, amplitude of the panicle, dimensions of calyx and length of pod, while the former should differ from C. macranthera sens. str. in loose and copious vesture. Northeastern Brazil and particularly the state of Bahia have now yielded plants (our var. micans) which combine the dense pilosity and small calyx proper to C. speciosa with the small leaflets and short pod of C. pudibunda; others (our var. calycosa) have the strigulose vesture, the leaflets and the long pod of C. macranthera with the ample calyx of C. pudibunda; and from northeastern Colombia we have var. lindeni, long mistaken for C. speciosa, which differs from the genuine Brazilian species of that name in the short pudibunda-like pod associated with exceptionally broad densely pilosulous leaflets resembling those of S. bacillaris var. benthamiana. The picture is further complicated by the existence of populations, unknown to Bentham, scattered around the west and north edges of the Amazon-Orinoco Hylaea in Venezuela and Peru that have introduced novel variations on the small-leaved theme of C. pudibunda far outside the reasonably expected range of what Bentham knew only as a local northeast Brazilian species. It should be emphasized that throughout this complex of forms the flower, except for great but continuous variation in size of calyx, remains essentially uniform. Our data are still deficient where pods and seeds are concerned, but such as we have suggest no fundamental differences between the described varieties. As redefined above, S. macranthera differs from closely related S. rugosa in the longer petiole and in absence of a petiolar gland between the distal pair of leaflets; and from S. angulata by the round branchlets and small caducous bracts. Differential characters of S. splendida and S. georgica, quite similar in form of perianth and androecium, are emphasized under those headings. A poor specimen from the Andean foothills in southern Santa Cruz, Bolivia (Charagua, 1000 m, V.1934, fl, Cardenas 2686, F), at present unidentified, is highly suggestive of an undescribed, remotely disjunct race of C. macranthera. It has the small neat foliage of var. micans or var. pudibunda, distantly allopatric in eastern Brazil, or of the north-Andean var. andina; but without good flowers or ripe fruits must remain an enigma until clarified by further collections.