Senna apsidoneura (H.S.Irwin & Barneby) 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, K! = NY Neg. 9194.
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Synonyms
Cassia apsidoneura H.S.Irwin & Barneby
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Description
Species Description - Reportedly suffruticose ±6 dm, the root unknown, wholly glabrous except for randomly setose-ciliate stipules and lfts and for appressed-puberulent pedicels and outer face of petals, the stems, petioles and pedicels prominently ribbed, the ample 2-foliolate, reticulately veiny concolorous lvs pallid-glaucescent. Stipules stiffly erect, linear-acuminate ±10 mm, commonly 3-nerved, charged toward tip with a few fine spreading setae 2-2.5 mm. Lvs 5-8.5(-?) cm; pulvinus and pulvinules ellipsoid 3-3.5 mm, wrinkled when dry; petiolar gland 1, erect from between the pulvinules, narrowly ovoid-fusiform 3-3.5 x 1-1.4 mm, purplish; lfts tilted backward from tip of petiole, turned half face-to-face, to bring the midrib to horizontal, the plane, stiffly chartaceous blades in outline obliquely reniform obtuse, minutely mucronulate, 2.5-5.5 x 5.3-6.6 cm, at base broadly flabellate or truncate, from base 5-nerved by the straight midrib and on its broad side 3, on its narrow side 1 short, incurved-ascending primary nerves, the midrib thence penniveined with 5-8 pairs of major obliquely ascending camptodrome secondary veins well within the sharp cartilaginous margin, these all again branched into a prominent quaternary reticulum of venules prominulous on both faces. Peduncles from upper lf-axils 1-3.5 cm, at apex 2-fld; bracts broadly subulate ±2 mm; pedicels at anthesis 1 + , in fruit to 2.5(-?) cm; sepals firmly herbaceous glabrous oblong-obovate obtuse to 8-9.5 mm, from base coarsely 4-6-nerved, the nerves branched distally; petals (presumably yellow) when dry pinkish-brown, subappressed-puberulent dorsally, all broadly obovate and contracted into a narrow claw ±2 mm, the vexillum deeply emarginate at apex, 20 x 11 mm, the rest obtuse, slightly longer, the 2 lateral plane, the 2 abaxial concave, enveloping the 3 long stamens; androecium 10-merous of 3 adaxial staminodes 5 mm, 4 intermediate fertile stamens each consisting of short stout filament and forwardly directed thecae 6.5-8 x 2 mm, and 3 abaxial fertile ones with filament ±6 mm and incurved thecae 10.5-12 x 2 mm, the 7 fertile all contracted at apex into a biporose beak ±0.4 mm; ovary strigulose; style strigulose, ±8 mm, slightly dilated and incurved at apex. Pod when half formed narrowly linear ±13 cm, the sutures already becoming prominent, probably subquadrangular when mature.—Collection: 1.
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Discussion
Senna apsidoneura has the petiolar gland, the few-flowered axillary racemes, the perianth and androecium, and the elongately linear pod of ser. Trigonelloideae, but stands alone in the series because of its bifoliolate, thick-textured, pallidly glaucescent leaves.