Orbexilum pedunculatum (Mill.) Rydb.
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Authority
Grimes, J. E. 1990. A revision of the New World species of Psoraleeae (Leguminosae: Papilionoideae). Mem. New York Bot. Gard. 61: 1-114.
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Family
Fabaceae
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Scientific Name
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Description
Species Description - Slender, sparingly strigose erect perennial to 0.75 m, glandular at least on upper leaflet surfaces, the stems many, or rarely single from each pseudoscape or root apex, arising from the swollen apical or subapical fusiform portions of woody roots, glabrate below, striate, stamineous to brown with age, the lowest nodes with cataphylls, these to 7 mm . Stipules erect, free, lineartriangular to triangular, 3-8 x 1-2 mm, prominently veined, upper ones decurrent, persistent. Leaves pinnately trifoliolate, the first one or two palmately trifoliolate with smaller elliptic leaflets, these quickly to tardily deciduous; leaves petiolate below, becoming subsessile above, the petiole 0.2-4.8 cm, at least faintly canaliculate, the base of different color and texture, usually somewhat constricted, 4-angled, lighter in color and less pubescent, jointed to stem; rachis 5-10 mm; petiolule 1.5-2 mm, blond, slightly wrinkled, strigose; leaflets elliptic-lanceolate, lanceolate or elliptic, 2.2-6.5 x 0.6-2.2 cm, apiculate at apex, rounded at the base, the upper surface glabrate to strigillose, dark brown-glandular, the lower surface strigillose, eglandular to glandular. Inflorescence elongate, with 15 to well over 50 nodes and 1-3 flowers per node, usually more densely strigose to subsericeous; peduncle 4.0-16.0 cm; rachis 2.0-12.0 cm, the internodes short, elongating to 1-5 mm in fruit; bracts quickly deciduous, trullate to caudate-lanceolate, 4-7 x 1.5-4 mm, stramineous to dark purple in color, glabrous, dark-brown glandular to eglandular; pedicels 1-2.5 mm . Flowers 5-7 mm; calyx sparingly pubescent, more densely so at base and at tooth margins, glandular or not, 2-4 mm long to upper teeth, 2.5-5 mm long to lower tooth, the tube 1-1.5 mm , the upper four teeth triangular, 1-2 mm , the lateral ones 0.25-0.5 mm longer than the upper two, the lower tooth lanceolate, 2-3 X 1 mm, in fruit the teeth flaring at throat, veins to tooth apices and sinuses becoming prominent, those to sinuses bifurcating and becoming marginal on teeth; petals purple to violet; banner ovate, 4.5-6 x 4-5 mm, the claw 4-5 mm , the blade obtuse at apex, the base scarcely biauriculate and internally callose; wings 4.5-6.5 X 2 mm, the claw 1-1.5 mm, the auricle 0.5 mm, this and adjacent ventral edge of blade callose; keel petals 3-4 x 1.5-2 mm, the claw 1-1.5 mm; androecium 3-3.5 mm, the anthers in two series, but all basifixed, or at most the attachment of those of the lower series slightly displaced to dorsal side, ovate-elliptic, less than 0.25 mm; gynoecium 2.5-3 mm, ovary glabrous. Fruit sigmoidally depressed-obovate in profile, 3-5 x 3.5-4 mm including a very short, downward arched beak, brown to green, glabrous, glandular to eglandular, rugose. Seed round-depressed-obovate, 3-3.5 x 2-2.5 mm, red-brown.
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Discussion
Typus infra sub var. pedunculato indicatur.
The varieties are usually easily distinguished; I have seen very few intermediate specimens. Along with the glandularity, there are some quantitative differences between the two, differences subject to too much overlap and exception to be diagnostic. Leaflets in var. gracile are from 2.3-6.0 x 6-19 mm , and as a rule are 2.5-5 times as long as broad. Those of var. pedunculatum are from 2.3-6.2 x 7-14 mm , and 3.3-7.2 times as long as broad. Also in var. gracile the hairs on the calyx and rachis are at most moderately dense, appressed, and 0.3-0.5 mm . The rachis and calyx of var. pedunculatum, on the other hand, are moderately to densely pubescent with erect to erect-ascending hairs 0.75- 1 mm.
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Distribution
In open woods and prairies, mostly in sandy but also rocky soils from 0-1500 m. In much of the eastern half of the United States from Ohio, Illinois and Indiana south to the Gulf States, and Kansas, Oklahoma and Texas east to the Atlantic seaboard.
United States of America North America| Ohio United States of America North America| Illinois United States of America North America| Indiana United States of America North America| Kansas United States of America North America| Oklahoma United States of America North America| Texas United States of America North America|