250 COMPOSITE. Ambrosia. 



A. hispida, Pursh. Perennial, spreading from a suffrutescent base, strigose-hispidulous or 

 hispid and hirsute : leaves all petioled, twice and thrice pinnatifid or interruptedly pinnately 

 divided into numerous short and small oblong ultimate lobes: sterile raceme commonly 

 solitary and elongated : fruit with a stout short beak and commonly 4 short acute tubercles. 



Fl. ii. 743, the original' in herb. Sherard was probably from Bahamas. A. crithmifolia, 



DC. Prodr. v. 525 ; Torr. & Gray, 1. c. — Sandy sea-shore, Florida. (W. Ind.) 



A. psilostaohya, DC. Perennial from slender running rootstocks, stouter than A. artemi- 

 siarfolia, 2 to 6 feet high, with strigose and some loose hirsute pubescence : leaves thickish; 

 upper simply and lower twice pinnatifid ; the lobes mostly lanceolate and acute : sterile 

 heads commonly short-pedicelled : fruit mostly solitary in the axils below, turgid-obovoid, 

 less than 2 lines long, rugose-reticulated, obtusely short-pointed, either wholly unarmed or 

 (sometimes on the same plant) with four short either blunt or acute tubercles. — Prodr. v. 

 526 ; Gray, PI. Wright, ii. 86, & Bot. Calif, i. 344. A. Peruviana, DC. 1. c, as to pi. Mex., 

 hardly of Willd. A. coronopifolia, Torr. & Gray, PI. ii. 291. A. Lindheimeriana & A. glan- 

 dulosa, Scheele in Linn. xxii. 156, 158. — Moist prairies and beds of streams, Illinois and 

 Saskatchewan to Texas, Arizona, and California. (Mex.) 



A. pumila, Gray. Perennial, a span or two high from slender running rootstocks, canes- 

 cent throughout with a dense and close silky pubescence, very leafy : leaves nearly all alter- 

 nate and long-petioled, 2-3-pinnately parted into linear-oblong crowded lobes : sterile heads 

 in a short spike: fruit obovoid, pubescent,- muticous, a line long (rarely two are connate at 

 hose). — Proc. Am. Acad. xvii. 217. Franseria pumila, Nutt. Trans. Am. Phil. Soc. 1. c. 

 344; Gray, Bot. Calif, i. 345, ii. 615. Hemiambrosia, Delpino, Stud. Comp. Artemis. 57. — 

 San Diego, California, Nuttall, &c, recently coll. by Cleveland in fruit. 



82. FRANSfiRIA, Cav. (Ant. Franser, a physician and botanist in 

 Madrid in the time of Cavanilles.) — Herbs or shrubby plants (all American) ; 

 with chiefly alternate leaves, some species with habit of Ambrosia and near it in 

 character, others with the fruiting involucre nearly that of Xanthium. — Cav. Ic. 

 ii. 78, t. 200 ; Willd. Hort. Berol. i. t. 2 ; DC. Prodr. v. 224 ; Torr. & Gray, 

 Fl. ii. 292. Franseria, Hemixanthidium, & Xanthidium, Delpino, Stud. Comp. 

 Artemis. 58—67. 



§ 1. Spines of the fruiting and 1-2-flowered involucre comparatively few, con- 

 ical, subulate, or flattened with the inner face more or less concave, usually 

 straight or merely incurved. — • § Acanthol&na, DC. 



# Herbaceous perennial : fruiting involucre seldom over a line long, in the same plant bearing 

 either one or two flowers. 



P. tenuif 61ia, Gkay. Erect, 1 to 5 feet high, leafy to the top, hispid, variously pubescent, 

 or glabrate : leaves mostly 2-3-pinnately parted or dissected into narrowly oblong or linear 

 lobes, and the narrow primary rhachis often with some interposed small lobes, the terminal 

 elongated : sterile racemes commonly elongated and paniculate : fertile heads in numerous 

 glomerules below, in fruit minutely glandular, usually 2-flowered, obovate with narrow 

 obpyramidal base, armed with 6 to 18 short and stout incurving spines, their tips almost 

 always hooked, and an excavated cartilaginously bordered areola above each. (Larger 

 leaves often 5 inches long or more.) — PI. Pendl. 80, PI. Wright, i. 104 (var. tripinna- 

 tifida), Bot. Mex. Bound. 87, & Bot. Calif, i. 346. Ambrosia longistylis, Gray, PI. Pendl. 79, 

 as to no. 407, perhaps of Nutt. Ambrosia tenuifolia, Spreng. Syst. iii. 851 1 A. confertiflora 

 & A. fruticosa (excl. var.), DC. Prodr. v. 525, 526. Xanthidium tenuifolium, Delpino, 1. c. 

 62. — Moist grounds, from Texas to N. Colorado, S. California, and southward. (Mex., 

 Hawaii, &c.) 



# # Herbaceous, with fruiting involucre 3 or 4 lines long at maturity, and longer stout or broad 

 spines : stems low. 



P. Hookeriana, Nutt. Diffusely spreading from an annual (or perennial'?) root, freely 

 branched, hirsute-pubescent or hispid, sometimes canescent with strigose-sericeous pubes- 

 cence when young : leaves of ovate or roundish circumscription (1 to 3 inches broad) and 

 bipinnatifid, or the upper oblong and pinnatifid : sterile racemes solitary or paniculate : fruit- 



