344 COMPOSITE. HymenocUa. 



with 9 to 12 broad and silvery-scarious persistent wings: corolla none. Akene as 

 in Ambrosia, &c. — Low and much branched shrubby plants, of arid deserts, Arte- 

 misia-like in habit ; with alternate linear-filiform leaves, minutely canescent beneath, 

 the lower sparingly piunately part.ed, and smaU heads sessile in profuse panicled 

 clusters. — PI. Fendl. 79 ; Torr. PI. Fremont, t. 8. 



1. H. Salsola, Torr. & Gray. Fruiting involucre spindle-shaped and strobile- 

 like, being covered with the spirally disposed orbicular scales (each a quarter of an 

 inch long), which are imbricated when moist, but spreading when mature and dry. 



Sandy saline uplands near the Moliave River {Fremont, Cooper), and through the desert mterior 

 to N. W. Nevada, on the borders of California, Watson, Lemmon. 



2. H. monogyra, Torr. & Gray. Fruiting involucre smaller (2 lines long), 

 bearing at the middle a single whorl of obovate or rhombic-reniform radiating scales. 



River bottoms, San Diego {Cleveland), thence to the Gila : not rare in Arizona, &e. Plant 

 3 to 5 feet high. The young plant so named in the Botany of King's Expedition belongs to the 

 preceding species. 



40. AMBROSIA, Toum. Ragweed. 

 Heads homogamous and unisexual, monoecious (sometimes nearly dicecious) ; the 

 pistillate one-flowered, mostly in the axils of upper leaves ; the staminate several- 

 flowered in panicled or single terminal racemes or spikes, without bracts. Stami- 

 nate flowers in an open several-lobed or almost entire truncate herbaceous involucre, 

 subtended by slender or filiform chafl'; their corollas broad and 5toothed ; their 

 anthers ahnost distuict, tipped with a slender-acuminate inflexed appendage ; ovary 

 and stigma none or rudimentary ; style with truncate tip radiately fimbriate. Pis- 

 tillate flower in a closed akene-like one-celled involucre, which at maturity is armed 

 below the short rigid beak with a single row of 4 to 8 tubercles or short spines, or 

 sometimes naked : corolla none. Akene ovoid or obovate, thick : pappus none. — 

 Weedy coarse annuals, or perennials, with mostly lobed, pinnatifid, or pinnately 

 divided and cleft leaves, the lower at least opposite ; the small heads greenish, or 

 the sterile flowers barely yellowish. Chiefly American and widely difi'used, but 

 apparently very scanty in California. 



1 A artemisicefolia, Linn. Annual, 1 to 3 feet high, roughish-hirsute : 

 leaves thinnish, twice pinnatifid : fruit (i. e. fruiting involucre) smooth below, not 

 reticulated, armed with about 6 very acute horns or spines. 



This, the common Eoman Wormwood or Bitterivced of the East, can hardly be absent from 

 California. S. Watson collected it in Nevada, and others m Oregon. 



2 A psilostachya, DC. Perennial, more strigosely hirsute than the forego- 

 in-, with thicker and less divided leaves, the upper only once pmnatificl : fruit 

 puberulent, rugose-reticulated, without horns or spines, or with short and rather 

 blunt ones.— ^. carompifolia, Torr. & Gray, Fl. h. 291. 



San Luis Rey {GmXter, Parry) ; Bay of San Francisco {Pickering and Brackcnridcje) ; San 

 Diego Co., Palmer. Also in Nevada, and thence eastward to Texas and Illinois. 



41. FRANSERIA, Cav. 

 Heads, flowers, &e., as in Ambrosia, except that the fertile involucre is armed 

 with more than one rank of prickles or spines, and is 1-4-celied and 1-4-flowered. 

 — All American herbs or suil'rutescent plants; the greater part Xorth American 

 west of the Mississippi. 



