250 COMPOSITE. Ambrosia. 



A. hispida, Prnsii. Perennial, spreading from a suffrntescent hase, strigose-hispidulous or 

 hispid and hirsute : leaves all petioled, twice and thrice pinuatifid or interruptedly pinnatelv 

 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. ( \V. Iiicl.) 



A. psilostadiya, DC. Perennial from slender running rootstocks, stouter than A. arfemi- 

 sic folia, 2 to 6 feet high, witli strigose and some loose hirsute pubescence: leaves thickish ; 

 upper simplv and lower twice pinuatifid ; the lobes mostly lanceolate and acute : sterile 

 heads commonly short-pedicclled : 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, PL Wright, ii. 86, Bot. Calif, i. 344. A. Pcrxi-iana, DC. 1. c ., as to pi. ilex., 

 hardly of Willd. A. coronopi folia, Torr. & Gray, Fl. ii. 291. A. LinJIninnnnna &. A. ylttn- 

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

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



A. puniila, GUAY. 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 

 base). Proc. Am. Acad. xvii. 217. Fr<mx< rla jnimi/a, Nutt. Trans. Am. Phil. Soc. 1. c. 

 344; Gray, Bot. Calif, i. 345, ii. 015. Hemiambrosia, Delpiuo, Stud. Comp. Artemis. 57. 

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



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

 Madrid in the time of Oavanilles.) --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 Xanthintn. Cav. Ic. 

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

 Fl. ii. 292.* Franseria, ffemixant/tidium, & Xanthidium, Delpiuo, 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. Acantholcena, DC. 



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

 either one or two flowers. 



P. tenuifolia, GRAY. Erect, l.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-rlowered, obovate with narrow 

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

 always hooked, and an excavated cartilaginous] v bordered areola above each. (Larger 

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

 tifida), Bot. Mex. Bound. 87, & Bot. Calif, i. 34G. Ambrosia longistylis, Gray, PL Fendl. 79, 

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

 & A. fruiicosa (excl. var.), DC. Prodr. v. 525, 52G. Xanthidium tcim! folium, Delpiuo, 1. c. 

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

 Hawaii, &c.) 



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

 spines : stems low. 



F. Hookeriana, NUTT. Diffusely spreading from an annual (or perennial?) root, freely 

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

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

 bipiunatind, or the upper oblong and pinuatifid: sterile racemes solitary or paniculate : fruit- 



