Hymenoclea. COMPOSITE. 343 



4 

 37. OXYTENIA, Nutt. 



Head heterogamous, discoid, about 5 marginal flowers pistillate and apetalous, 

 consisting merely of ovary and 2-cleft style; the other flowers 10 to 20, staminate 

 (their ovary and stigma abortive), with funnelform 5-lobed corolla and undivided 

 style, and nearly distinct anthers, these with blunt tips. Involucre of about 5 thin 

 and broad scales. Receptacle chaffy, a spatulate villous scale subtending each or 

 most of the sterile flowers and falling with them. Akenes obovate, turgid, beset 

 with long villous hairs, crowned (at least when young) with a large and protu- 

 berant annular disk. Pappus none. Genus nearly related to the next, of one 

 species, viz. 



1. O. acerosa, Nutt. Shrubby, 3 or 5 feet high, whitened with a fine pubes- 

 cence : branches rigid, rush-like, mostly naked, terminated by the racemose or 

 paniculate-clustered inflorescence of small woolly heads : leaves as far as known 

 alternate, either pinnately 3 5-foliolate or the uppermost simple and like the leaf- 

 lets, i. e. very narrowly linear and revolute so as to appear filiform or acerose, 2 to 4 

 inches long, rigid. PI. Gamb. 172. 



Southeastern borders of California and adjacent parts of Arizona, in a desert region, Gambel, 



Lieut. Wheeler. 



38. IVA, Linn. 



Head heterogamous, discoid ; a few marginal flowers pistillate and with a short 

 tubular corolla ; the other and more numerous flowers staminate (their ovary and 

 stigma abortive), with funnelform 5-lobed corolla and undivided style : anthers 

 nearly distinct. Scales of the involucre few and mostly in a single series, commonly 

 united into a cup. Receptacle chaffy with linear or spatulate scales subtending 

 sterile flowers. Akenes obovate, thick, naked, often granulate ; no disk at the apex. 

 - Leaves simple, at least some of the lower opposite. Heads small, nodding on 

 short pedicels, either in the axils of the leaves, or in terminal spikes or panicles. 



A genus of several species on the eastern side of the continent, one of which extends from the 

 Missouri Eiver to the Pacific, viz. 



1. I. axillaris, Pursh. Perennial, branching, a span to a foot and a half high, 

 varying from minutely hirsute to glabrous, and the sessile entire leaves from 

 broadly linear to spatulate or obovate (about an inch long) : heads solitary in their 

 axils, hemispherical : scales of involucre about 5, broad, united at base or beyond 

 the middle. 



Var. pubescens. Villous with lax spreading hairs ; the involucre turbinate and 

 almost entire. Gray in Bot. Wilkes Exp. 350. 



Sandy and usually saline soil, near the coast, also along the western borders of the State, and 

 north to British Columbia. The variety from Bay of San Francisco. 



39. HYMENOCLEA, Torr. & Gray. 



Heads homogamous and unisexual, monoecious ; the staminate ones many-flow- 

 ered ; the pistillate one-flowered ; the two kinds intermixed in the axillary sessile 

 clusters, or the staminate in upper axils. Staminate flowers in a hemispherical 

 head, with an open 5 - 6-lobed involucre, similar to those of Ambrosia (only the 

 chaff of the receptacle is much dilated, and the inflexed tip of the anthers is blunt) : 

 pistillate flower solitary in a closed and akene-like involucre, which is pointed with 

 a slender beak from the tip of which the style protrudes, its middle adorned 



