148 COMPOSITAE 
3. Ambrosia psilostachya DC. Common Ragweed. Fig. 5218. 
Ambrosia psilostachya DC. Prod. 5: > 
mbrosia coronopifolia Torr. oe ira 1. N. Amer. 2: 291: 1842, 
paris sia scalifornc Rydb. mer. a 33: 1922, 
Ambrosia psilostachya var. pa Sonssh Blake in es. Contr. U.S. Nat. Herb. 25: 581. 1925, 
Per ie the stems pikomg scattered, 0.3-1 m. high, from running rootstocks, a or 
hirsute with = esting or spreading hairs, sally branched at least above. Leaves oppo 
1 te angular in ou tline, 4-10 ¢ ong, on usually short-winged petioles, thickish, 
shallowly or r deeply — with fate ae acute, alten toothed or lobed, forward-pointing 
divisions, strigose or ascending-hirsute or -hispid a nd glandular, the aoe narrower and less 
divided, ofte Satie re; staminate heads 1- eds in diameter, in usually elongate an 
n hs nln s, about ‘1 fe) s 
hairs; pistillate heads solitary or eng is in the upper axils; fruit obovoid, about m. long 
(the short blunt beak about 0.6 mm. long), glandular, hirsute, often rugose, boat Bg or with 
1-6 short, obtuse or acute, conic a around apex = mene 
Dry or moist places, Sono and Transition Zones; comm we in California, Arizona, and northern 
Mexico and in Washington, =e hoad pr eg introduced; also lilin eatin en Type locality: between 
San F saloon and Matamoros, Tamaulipas. Collected by Rertaier April—Oct 
4. Ambrosia pumila (Nutt.) A. Gray. San Diego Ragweed. Fig. 5219. 
Franseria pumila Nutt. Trans. Amer. Phil. oo II. 7: 344. 1840. 
Hemiambrosia eterocephal ae iwet "Studi L gn. Anem. 61. 1871. 
Ambrosia pumila A. Gray, Proc. Amer. Acad. 205 217. 1882, 
ae herb 1-2.5 dm. high with running rootstocks; stems erect, canescent- ot ge at 
least when young, with mostly appressed hairs and sparsely hispid. Leaves mostly alternate, ovate 
i i 0 ] 
or oblong in outline, bi- or tripinnatifid, 5-10 cm. long including petiole, apn ego nd ee 
silky-pilose wee mo stly appressed hairs, the ultimate divisions mostly linear-oblong, obtusish, 
cro ss wide; staminate heads about 25-flowered, short-pediceed in bs short = 
the nvoluere cresaie lobed: pilose ; pistillate heads clustered in the axils of reduc AVES; 
frit rm is d, 2-2.5 mm. long, pubescent, longitudinally ribbed below, lgoiraly. pak arly scte 
Alkaline — Sonoran Zones; southern San Diego County, Califorriia, southward to central Lower California. 
Type locality: near San Diego. June—Sept. 
FRANSERIA Cav. Ic. 2: 78. 1793. 
Heads i wae! the staminate nodding, in n ebracteate terminal racemes, the Sota sessile 
2 : ay ; th 
x 
heads many-flowered, the involucre gamophyllous, saucer-shaped or turbinate, crenate, 
nut-like or bur-like, bearing few to many straight or hooked, rigid s spines in 2 or more 
series, the beaks conic, opening obliquely, often econ 2-toothed. Staminate nies 
mostly funnelform, 5-toothed : corolla wanting in pistillate flowers. Stamens 5; filaments 
connate or lightly coherent; anthers lightly coherent, subentire at base, with ovate or 
deltoid, terminal appentieel often ti ped with an inflexed cusp. Style in staminate flowers 
ndivided, at apex slightly dilated ae ‘imbr iate ; in pistillate flowers with 2 linear, exserted, 
sti atic branches. Achenes usually obovoid, tightly enclosed by the fr ruiting involucre, 
glabrous, epappose. [Name in honor of Acetone Franser, physician and botanist of Ma- 
drid.] 
A genus of about 30 species, all American, mostly North American but a few on the western coast of South 
America. Type species, Franseria ambrosioides Cav. 
Herbs. 
Annual; staminate involucre with 3 of the nerves thickened and blackish rages 8 fruit armed with flattened 
straight spines, . F. acanthicar rpa. 
Perennial; nerves of the er involucre not thickened and blackish below 
Erect; cokes -4 mm. long, obovoid, cin pid 10-20 hooked spines 0. 8 ek -_ or less; leaves usually 
greenish, m eee. or less sparsely strigos cies Ba tiflora. 
Pramaiiea: fruit — or fusiform, 6~9 mm. long, the spines not me pu mm. long; leaves densely 
ca ae strigo: 
ostly eate or obovate, crenate-serrate. 3. F. chamissonis, 
takes bi. to erence ie oa cheutameais bipinnatisecta. 
Shrubby or suffru 
Leaves antalya = ee — the lower stem-leaves not more than 4 or 5 cm. long. 
Leaves Bh oomeas 4 canescent-strigilose, bi- to tripinnately divided into small, —: ovate or obovate divi- 
sions; fruit pe da and sparsely pilose. . F. dum 
