296 FLORA OF TEXAS. 



leaves tliiu; the earliest ones ovate, sharply serrate or 

 toothed, long-petioled, the other 3-parted, with the middle 

 segment lanceolate and commonly 3-toothed ; leaves of the 

 involucre subulate, longer or shorter than the oblong 

 head ; hrads spatulate, obtuse, barely exceeding the calyx. 

 Annual; stems o'-lO' long; floiuers blue. 



E. DiFFUSUM. Leaves all sessile and palmately parted; 

 segments oblong, incisely serrate and spinose ; stem dicho- 

 tomously branched, diffuse ; heads subglobose, nearly ses- 

 sile ; leaflets of the involucre 4-6, 3-cleft, a little longer 

 than the heads ; scales lanceolate, entire. Witchita Moun- 

 tains. — Marcy. 



E. COEOXATUM. Cauline leaves palmately 5-7-parted ; 

 divisions pinnatifid-lancinate, with narrow spinose seg- 

 ments; leaflets oi the involucre 9-12, lanceolate, entire, 

 spiny at the tip, twice as long as the flowers ; the terminal 

 ones leafy and crowning the head; stem about 3°-4° high, 

 with erect branches; cauline leaves 2'-4' in diameter; 

 heads ^' in diameter, crowned with several foliaceous spi- 

 nose-dentate scales ; calyx-iwhe, clothed with acute vesicular 

 scales. — Drummond. 



E. Leavexworthii. Stem stout, about l°-2° high ; 

 cauline leaves palmately 5-7-parted, 2' long; peduncles V 

 long; licadSy exclw^iTQ of crown, 1-1 J' long and nearly 1' 

 in diameter, the axis proliferous and bearing a tuft of 

 leaves at the summit resembling those of the involucre; 

 calyx-\ohQ?> pinnatifidly 3-5-cuspidate, clothed with obtuse 

 scales ; the heads and upper part of the stem usually of a 

 bright violet-purple color. — Drummond. 



E. AQUATicuM, Linn. {Button Snaheroot.) Leaves 

 broadly linear, with straight and simple parallel veins, re- 

 motely ciliate with soft spines; leaflets of the involucels 

 mostly entire, shorter than the ovate-globose pedunculate 

 heads; scales entire. Variable in size and in breadth of 



