204 
Spring Flora of Oklahoma 
Annual or biennial species, with stems leafy throughout. 
1. S. glabellus. 
Perennial species, mostly with rootstocks. 
Leaves and stems more or less persistently woolly or 
tomentose. 2. S. plattensis. 
Plants glabrous, or nearly so, at least when mature, 
the stem sometimes at the base. 3. S. obovatus. 
1. Senecio glabellus Poir. Cress-leaved Groundsel. Annual, 
glabrous throughout, fleshy and tender. Stem hollow, l°-3° high. 
Leaves pinnately divided, the segments sinuate-dentate, entire or 
lobed. Heads numerous, 7"-10" broad, in terminal corymbs. Rays 
6-12. Achenes minutely hispidulous on some of the angles. Pappus 
white, somewhat longer than the involucre. 
In moist soil. April-September. Infrequent. 
2. Senecio plattensis Nutt. Prairie Ragwort. Perennial, more 
or less tomentose, or becoming glabrate in age, seldom over 18' high 
Basal leaves oval, ovate or oblong, more or less pinnatifid, crenulate 
or dentate, long-petioled. Stem leaves smaller and usually pinnatifid. 
Heads several or numerous, corymbose. 
Dry soil. April-June. Common. 
3. Senecio obovatus Muhl. Round-leaf Squaw-weed. Peren¬ 
nial. Stems glabrous, or a little woolly at the base, 9'-24' high. 
Leaves glabrous, the basal ones obovate with a cuneate base, broadly 
spatulate, crenate-dentate, often purplish. Stem leaves spatulate to 
oblong, often incised or pinnatifid. Heads several, corymbose, 6"-8" 
broad. Rays 8-12. Achenes glabrous. Pappus white. 
In moist soil. April-June. Turner Palls. 
XXVII. CIRSIUM (Tourn.) Mill 
Erect, branching or simple, prickly herbs. Leaves al¬ 
ternate or basal, sinuate-dentate, lobed or pinnatifid, usu¬ 
ally very spiny. Heads large, many-flowered, solitary or 
clustered, of purple, yellow, or white, tubular, perfect, and 
fertile, or, rarely, dioecious flowers. Involucre ovoid, or glob¬ 
ose, bract prickle-tipped or unarmed, imbricated in many 
series. Receptacle flat or convex, bristly. Achenes obovate 
or oblong, compressed or obtusely 4-angled, glabrous, smooth 
or ribbed. Pappus of several series of slender, plumose 
bristles, connate at the base. 
Leaves glabrous or hispid above, tomentose beneath. 
1. C. virginianum. 
