COMPOSIT.E. (COMPOSlTi: FAMILY.) 181 



cultivated grounds iicross the continent, known varionslv as " lioman Worm- 

 wood," " Ragweed," and " Bitter-weed." 



3. A. psilostachya, DC. From slender running rootstocks, stouter, 2 

 to 6 feet lu(jh, with strigose and some loose hirsute pubescence : leaves thickish; 

 upper simpli/ and lower twice pinnatijid ; the lobes mostly lanceolate and acute: 

 sterile heads commonly short-pedicelled : fruit mostly solitary iu the axils 

 below, rugose-reticulated, obtusely short-pointed, either wholli/ unarmed or with 

 four short either blunt or acute tubercles. — From the Saskatchcwuu to Texas 

 and westward across the continent. 



29. FRANSERIA, Cav. 



Ours are herbaceous, with chiefly alternate leaves, and the spines (jf the 

 fruiting and 1 to 2-flowered involucre comparatively few. 



* Fruiting involucre seldom over a line long, in the same plant beariw/ either 

 1 or 2 flowers. 



1. F. tenuifolia, Gray. Erect, 1 to 5 feet high, leafy to the top, hispid, 

 variously pubescent, or glabrate : leaves mostly 2 to 3-pinnately parted or dis- 

 sected into narrowly oblong or linear lobes, the terminal elongated: sterile 

 racemes commonly elongated and paniculate : fertile heads in numerous glom- 

 erules below, in fruit minutely glandular, usually 2-flowered, armed with 6 

 to 18 short and stout incurving spines, their tips almost always hooked, and 

 an excavated cartilaginously bordered areola above each. — PI. Feudl. 80. 

 From Colorado to California, Texas, aud southward. 



* * Fruiting involucre 3 or 4 lines long at maturiti/, and longer stout or broad 

 spines : stems low. 



2. F. Hookeriana, Nutt. Diffusehj spreading from an annual root, freely 

 branched, hirsute-pubescent or hispid: leaves of ovate or roundish outline, 1 to 

 3 inches broad, and bipinnatifid, or the upper oblong and pinnatijid: sterile 

 racemes solitary or paniculate : fruiting involucre armed with flat and thin 

 lanceolate-subulate smooth and glabrous long and straight spines, \-flowered. — 

 From the Saskatchewan to Texas and westward across the continent. 



3. F. discolor, Nutt. A foot or less high, erect from perennial slender 

 creeping root-stocks : leaves canescentli/ tomentosn beneath, green and glabrate al>ore, 

 interruptedly-pinnatijid, oblong in outline, comparatively large, the lowest often 

 6 inches long; the lobes usually short and broad: sterile racemes commonly 

 solitary : fruiting involucre 2-flowered, canescent, armed with rather short mnicaJ- 

 subulate very acute and straight spines. — Plains, Nebrask:i tn Wyoming, Colo- 

 rado, and New Mexico. 



4. F. tomentosa, Gray. A foot high, rather stout, erect, from an appar- 

 ently perennial base, canescent icith a dense sericeous tomentum: leaves very white 

 beneath, cinereous above, pinnately 3 to 5-clefi or parted : the terminal division 

 large, ol)long or broadly lanceolate, serrate ; upper lateral .•similar but smaller ; 

 lowest commonly very small and entire : fruiting involucre 3 lines long. 2- 

 fiowered, nearly glabrous ; the short spines conical -subulate, very atute. and the 

 very tip usually uncinate-incurved. — PI. Fendl. 80. Along streams or river 

 beds, Kansas and E. Colorado. 



