Senna lindheimeriana

Title

Senna lindheimeriana

Authors

Howard S. Irwin, Rupert C. Barneby

Scientific Name

Senna lindheimeriana (Scheele) H.S.Irwin & Barneby

Description

73.  Senna lindheimeriana (Scheele) Irwin & Barneby, Phytologia 44(7): 500. 1979. Cassia lindheimeriana [sic] Scheele, Linnaea 21: 457. 1848.—. . nordlich von Neubraunfels [=New Braunfels, Comal Co., Texas]: Lindheimer."—Holotypus, †B; neoholotypus, provisionally proposed by Isely, 1975, p. 204; Lindheimer III/380, NY! isotypi, GH, MO!-Earleocassia lindheimeriana Britton ex Britton & Rose, N. Amer. Fl. 23(4): 249. 1930.

Cassia lindheimeriana sensu Bentham, 1871, p. 530; Wooton & Standley, 1915, p. 334; Kearney & Peebles, 1951, p. 406; Turner, 1959, p. 76, map 38 (Texas); Isely, 1975, p. 109, map 47 (U.S.A.); Correll & Johnston, 1970, p. 791.

Stout, amply leafy herbs with 1-several erect or assurgent stems (2-)3-12(-15) dm arising annually from a blackish root and ultimately a shortly branched caudex, the stems and lf-stalks densely pilosulous or subvelutinous with fine erect or widely descending straight hairs up to 0.3-1 mm usually mixed with either shorter, antrorsely accumbent or minute clavate yellowish hairs (frequently with both) and the inflorescence and some lfts sometimes charged in addition with few random fine weak setae up to 1.5-2.5 mm, the pallid-green lfts subappressed- pilosulous on both faces, usually yellowish-green above and ashen beneath, the inflorescence of axillary racemes at first lateral to stem and either longer or shorter than the subtending lf, later or sooner forming a shortly exserted corymbose panicle.

Stipules erratically ascending, spreading or deflexed, the herbaceous lance- attenuate or -caudate blade 8-18 x 1-2.5 mm, early dry caducous.

Lvs below inflorescence 6-16 cm (some distal ones, not further described, shorter); petiole including firm, scarcely swollen pulvinus (l-)1.5-4.5(-6) cm, at middle 0.6-1.7 mm diam, bluntly 3-ribbed dorso-laterally, narrowly grooved ventrally; rachis 1.5-8(-10.5) cm; glands between all pairs or all but the distal pair of lfts stipitate, in profile (1-) 1.5-5 mm, the slender stipe pilosulous, the narrowly subuliform or linear-fusiform acute head 0.1-0.35 mm diam, not or little wider than stipe; lfts 4-8, in most lvs of most plants 5-7 pairs, the proximal pair smallest but otherwise little graduated, the penultimate often a little longer than the distal, all asymmetrically oblong-, ovate- or obovate-elliptic, obtuse mucronate or apiculately acute, the larger ones 20-46(-50) x 8-18(-20) mm, 1.9-3.2(-3.5) times as long as wide, at base cordate on proximal and either rounded or cuneate on distal side, the plane margin often a trifle thickened, the midrib carinate dorsally, immersed or weakly prominulous above, giving rise dorsally on proximal or on both sides to (2-)3-6(-7) secondary veins, these usually expiring well within the margin, sometimes weakly camptodrome.

Racemes loosely (5-)7-25-fld, the axis and peduncle together becoming (3-)5-14 cm; bracts resembling stipules in form and texture (3-)4-13 mm, early brown dry, deciduous before or at anthesis, some rarely more persistent; pedicels (6-) 10-22 mm, little thickened in fruit; young fl-buds nodding, obovoid or oblong- ellipsoid obtuse pilosulous; sepals pale green, pinkish or rarely subpetaloid and yellow, elliptic or oblong-obovate of subequal length but the innermost a little broader and membranous-margined, the longest (5-)6-8.5(-9) mm; petals subequal, light bright yellow drying whitish or stramineous brown-veined, in outline obovate- or oblong-obovate-cuneate (10.5-) 11.5-16 mm, expanding and withering in one day; androecium glabrous, functionally 7-merous, the 3 adaxial staminodes narrowly spatulate, the 7 fertile stamens subhomomorphic except the 2 next the staminodes a trifle shorter, the filaments 1.4-2.7 mm, the anthers all narrowly lanceolate in profile, lunately incurved, the larger of a set 3-5.1 x 0.6-0.7 mm, just below apex strangulated and then a little dilated, dehiscent by an oblique terminal pore, the thecae bicolored, the connectival grooves and dorsoventral faces brown, the sutural faces yellow (exceptionally all yellow); ovary densely white-pilosulous; style glabrous linear-attenuate incurved 1.2-2.2 x 0.1-0.2 mm, the minute stigmatic cavity obliquely terminal; ovules 20-28.

Pod ascending or sometimes spreading in age, sessile or almost so but sometimes attenuate at base and pseudostipitate, in profile linear, gently incurved, (3-)3.5-6.5 x (0.5-)0.6-0.85(-0.9) cm, abruptly contracted at apex into a subulate beak, strongly compressed laterally, 3-carinate ventrally, the thin green or purplish valves becoming brown or blackish except for paler sutural margins, at first plane but a little distended and low-corrugated over the seeds, thinly strigose with appressed straight hairs up to 0.6-1.2 mm, inertly dehiscent downward through both sutures, the interseminal septa very narrow, the cavity therefore continuous; seeds 1-seriate and separated by distances about equal to their narrow diameter, most of them turned with broader face to the septa but 1 at each end often turned to face the valves, compressed but plump, in broader outline obovate or oblong-obovate 3-4.8 x 1.8-3.2 mm, often distorted or deformed, the testa brown, dull, minutely rugulose overall or when fully ripe becoming smooth and crackled, the areole elliptic or oblong-elliptic 0.4-1 x 0.3-0.6 mm; n = 14.—Collections: 69.

Stony hillsides, washes, talus under cliffs, in Larrea scrub, mesquite grassland and chaparral, 200-1900(-2100) m, widespread, mostly on limestone, over the n. Chihuahuan Desert in trans-Pecos Texas, s. New Mexico, extreme s.-e. Arizona (Cochise Co.), n.-e. Sonora (rio Bavispe), centr. Chihuahua, thence s.-e. in Texas down the Rio Grande valley and along the s. margins of Edwards Plateau to the Colorado valley and Balcones Escarpment, and in Mexico interruptedly to e.- centr. Coahuila and the e. foothills of Sa. Madre Oriental in Nuevo Leon and Tamaulipas, there extending s. just to the Tropic of Cancer; reported (Isely, l.c.) from the Gulf Coastal Plain in Cameron Co., Texas, where perhaps only adven- tive.—Fl. IV-XI, the fruits long persisting.—Pata de Buey (Chihuahua).

A handsome but somewhat coarse herbaceous senna, the pallid silvery-gray foliage contrasting effectively with the panicle of golden flowers. It is widely sympatric with related S. roemeriana, but obviously different, most distinctively in the several pairs, not exactly one pair, of leaflets. In southeastern Arizona and adjoining New Mexico the range of S. lindheimeriana overlaps that of S. covesii, which is, however, readily distinguished by the narrow, setiform stipules, fewer (mostly 2-4, not 4-8) pairs of leaflets, fewer (mostly 4-8, not 7-25)-flowered racemes and particularly by the short turgid pod that contains more numerous seeds stacked contiguously into two files. More closely related is the south Mexican, fully tropical S. foetidissima, similar in stature, in broad herbaceous stipules, in number of leaflets and in uniseriate seeds; this differs, however, in the malodorous, bright green, not pallid foliage, in the elongate anthers (5-12, not 3-5 mm) and style (3-5, not 1.2-2.2 mm) and in the genuinely stipitate turgid (not subsessile and strongly compressed) pod.