GENERA OF NORTH AMERICAN FABACEAE VII. ASTRAGALUS AND RELATED GENERA (CONTINUED)

Abstract

Annual or perennial herbs. The leaves are alternate, odd-pinnate, with several or many leaflets. The flowers are perfect, in axillary racemes. The calyx-tube is campanulate, the teeth subulate. The corolla is purple or white, rarely ochroleucous. The banner is broadly obovate, subsessile. The wings are clawed, the blade obliquely oblanceolate or lunate, with a reflexed auricle, free. The keel-petals are adnate, clawed, the blades broadly lunate, in two American species produced into a small beak. The stamens are diadelphous (9 and I), the sheath is straight, the free upper part of the filaments curved upwards. The ovary is many-ovuled, the style curved, the stigma minute, terminal. The pod is elongate, sessile, linear or oblong, or rarely lance-oblong in outline, usually somewhat compressed, rarely terete, coriaceous, or rarely membranous, not inflated, completely (or in one species incompletely) 2-celled, the septum meeting the upper suture. The seeds are obliquely reniform. ILLUSTRATION: Plate XVI U. Hamosa Nuttalliana (DC.) Rydb., X 2/3; I. calyx; 2. banner; 3. wing; 4. keel-petal; 5. stamens; 6. pistil, X 2; 7. pod; 8. pod in longitudinal section, the septum partly removed to show the seeds, X I; 9. pod in cross-section; IO. seed, X 2. SYNONYM: Hamaria Fourr, Ann. Soc. Linn. Lyon, II. i6: 364. i868. Fourreau changed the name to Hamaria, a noun meaning a bearer or user of hooks, as hamosa is an adjective, meaning full of or abundant in hooks. Medicus, who established the genus on Astragalus hamosus L., used the feminine adjective form of the specific name as generic name. He also used several other specific adjectives in a similar way for his genera. The worst of these is perhaps Contortuplicata, another genus of this group. In the type species, Astragalus hamosus, the pod is much elongate, semiwoody or firmly leathery, completely 2-celled, and strongly curved. The main difference between Hamosa and Astragalus, in a restricted sense, is the elongate, spreading, or reflexed pod of the former. Only in a few of the species (in none of the American ones), the pod is as much curved as in the type; in many of them the pod is straight. In the North American species the texture of the valves is less thick and less firm, in some submembranous. In one species, Hamosa imperfecta, the septum does not meet the upper suture, but in every other respect the structure of the pod and the habit of the plant agrees perfectly with the other species of the section LEPTOCARPAE. In two species, H. nothoxys and H. acutirostris,