POLYGONS^:. 49 



2. C. robusta, Parry. Stout, erect, 6 18 in. high, dichotomously 

 branched, the main stem below with several whorls of oblanceolate 

 petiolate leaves; herbage hirsute, the inflorescence and growing parts 

 almost canescently so: capitate cymes sessile and solitary in the lower 

 forks, several and peduncled along the upper branches : bracts linear, 

 with acerose tips: involucres oblong-campanulate, sharply angled; seg- 

 ments unequal, the scarious margin very narrow, purplish, the uncinate 

 teeth not widely spreading: perianth short-pedicellate; lobes nearly 

 equal, erose-denticulate and mucronulate. In dry sandy soil at Ala- 

 meda. June Sept. 



M- -M- Lobes of involucre without scarious margins. 



3. C. valida, Wats. Stout, 618 in. high, branching above, villous: 

 lower leaves oblanceolate, 1 in. long, on long petioles: involucres in 

 dense heads 2 3 lines long, the lobes nearly equal, slightly spreading, 

 the awns straight : perianth subsessile, narrowly tubular, 2% lines long, 

 villous or glabrous, cleft one-third of the length, the lobes oblong, very 

 unequal, the shorter ones erose: filaments adnate to the middle or even 

 higher. In Sonoma Co., near Petaluma, etc. 



* +- Of diffuse habit; involucres scattered, or in loose clusters. 

 M- Lobes of involucre with narrow scarious margins. 



4. C. pungens, Benth. Branches prostrate, 6 12 in. long, hirsute- 

 pubescent: leaves spatulate or oblanceolate, 1 in. long, mostly opposite; 

 bracts similar but narrower, acerose at apex: involucres crowded on 

 short lateral branchle ts, 1% 2 lines long, unequally toothed, usually 

 margined; teeth strongly uncinate: perianth obconic, subsessile, shortly 

 cleft; segments equal, oblong, entire: filaments more or less adnate to 

 the lower part of the tube. Sandy hills about San Francisco. 



M- -M- Lobes of involucre without scarious margins. 



5. C. cuspidata, Wats. Habit of C. pung^ns, leafy-bracted: leaves 

 narrowly oblanceolate, 1 in. long; floral bracts acerose: involucres 

 loosely cymose-clustered, 1 line long, 6-toothed, without scarious mar- 

 gins, the alternate teeth shorter, all arme d with hooked awns : perianth 

 subsessile, pinkish; lobes nearly equal, oblong, acutish, the strong nerve 

 excurrent as a short cusp. This was regarded by Dr. Parry as only a 

 form of C. pungtns; but by the description, it should be very distinct. 

 Sandy hills at San Francisco. 



6. C. Cleveland!, Parry. Prostrate or assurgent, the rather few 

 branches 23 in. long, villous-pubescent : leaves mostly radical, broadly 

 oblanceolate, narrowed to a rather long and slender petiole: involucres 

 soft-pubescent, the triquetrous tube contracted above; segments very 

 unequal, 3 as long as the tube, the other 3 scarcely half as long, all unci- 



