344 COMPOSITE. Hymenoclea. 



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 pinnately parted, and small 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 orbicula'r scales (each a quarter of an 

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



Sandy saline uplands near the Mohave River (Fremont, Cooper), and through the desert interior 

 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, &c. 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, Tourn. RAGWEED. 



Heads homogamous and unisexual, monoecious (sometimes nearly dioacious) ; 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 chaff; their corollas broad and 5-toothed; their 

 anthers almost distinct, 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 diffused, 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 Roman Wormwood or Bittcrweed of the East, can hardly be absent from 

 California. S. Wateon collected it in Nevada, and others in Oregon. 



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

 ing, with thicker and less divided leaves, the upper only once pinnatifid : fruit 

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

 blunt ones. A. cor onopif alia, Torr. & Gray, Fl. ii. 291. 



San Luis Rey (Coulter, Parry) ; Bay of San Francisco (Pickering and Brackenridge) ; San 

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



41. FRANSERIA, Cav. 



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

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

 All American herbs or suflrutescent plants; the greater part North American 

 west of the Mississippi. 



