Orbexilum pedunculatum (Mill.) Rydb. var. pedunculatum
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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 - Characters as in key; also, leaflets 2.3-6.5 x 0.7-1.4 cm; peduncle 6.5-17.0 cm; rachis 4.5- 9.5 cm, densely erect-appressed pubescent; hairs on calyx ascending-erect, 0.75-1.0 mm; upper two calyx teeth 1-1.5 mm , lateral teeth 1.5-2 mm , lower tooth 2-3 mm.
Distribution and Ecology - In woodlands from southern Ohio, Indiana and Illinois, south to Georgia, Mississippi, and Louisiana, west to Kansas (Cherokee Co.), eastern Oklahoma and eastern Texas.
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Discussion
Lectotypus, hb. Miller, B M (photo, ISTY!) that plant in the middle of the sheet with inflorescences 10-15 cm, with lower leaflets surfaces and calices eglandular, excluding the plant on the right hand side of the sheet with inflorescences 6 c m or shorter and lower leaflet surfaces and calices glandular. Desmodium pedunculatum (Mill.) D C , Prodr. 2: 338. 1825. Psoralea pedunculata (Mill.) Vail, Bull. Torrey Bot. Club 21: 114. 1894, non Ps. pedunculata Ker-GawL, Bot. Reg. 3: 223. 1817, nee Ps. pedunculata (Pursh) Poir., Encycl. Suppl. 4: 490. 1816.
Psoralea eglandulosa Elliott, Sketch bot. S. Carolina 2: 198. 1824, based with uncertainty on Melilotus psoralioides (Walter) Nutt., Gen. N. Amer. pi. 2: 104. 1818. Psoralea psoralioides var. eglandulosa (Elliott) Freeman, Rhodora 39: 426. 1937. Orbexilum pedunculatum var. eglandulosum (Elliott) Isely, Sida 11:432. 1986.
Occasional specimens of var. pedunculatum will have random glands on either the calyx tube or lower leaflet surface. However, they will not occur concomitantly. Individual flowers of var. pedunculatum infected with gall wasps are densely glandular on the calyx tube. A badly damaged sheet of Orbexilum pedunculatum exists in the Miller herbarium (BM). As reported by Weatherby (to Freeman, 1937), and contrary to the information supplied to Isely (1986), the sheet is indeed a mixture ofthe two varieties herein and historically recognized. In the center ofthe sheet is a large portion of a plant with two to three long racemes. T o the right of this is a smaller specimen with much shorter racemes. In accordance with Article 9 of the Rules, the lectotypus chosen must be that plant which corresponds most closely to the original description. The description does not mention glands. However, Miller refers to "racemis alaribus erectis longissimis" and later to ". . . very long bunches of flowers arising from the sides of the stalks." It would appear that the large plant in the center ofthe sheet with racemes 10-15 cm or longer is the plant Miller referred to, not the smaller specimen to the side with racemes scarcely 6 cm. Unfortunately, this radically changes the traditional concept of Orbexilum pedunculatum, for the larger plant is the eglandular variety, and O. pedunculatum var. pedunculatum must now apply to those plants long known as Psoralea psoralioides var. eglandulosa. The taxon long familiar to botanists of the eastern United States as Psoralea psoralioides (Walter) Cory var. psoralioides {Trifolium psoralioides Walter, Fl. carol. 184. 1788, nom. ambiguum) n ow takes the name Orbexilum pedunculatum var. gracile (Chapman) Grimes. Psoralea psoralioides is indeed an older available name for this glandular variety, but must be rejected as being ambiguous. The typus, reported in hb. Walter (CHARL), is lost according to Freeman (1937), but has been traditionally considered to be the glandular form. However, Nuttall transferred the name to Melilotus, precisely because he considered the plant to be eglandular. Until some evidence arises that dispels any doubt as to whether Walter's name applies to the glandular form, it must be considered ambiguous