polygone^;. 49 



2. C. robust;!, Parry. Stout, erect, 6 — 18 in. high, dichotomously 

 branched, the main stem below with several whorls of oblanoeolate 

 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. 



++ ++ Lobes of involucre without scarious margins. 



3. C. valida, Wats. Stout, 6 — 18 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. 



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



•m- Lobes of .involucre with narrow scarious margins. 



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

 pubescent: leaves Bpatulate 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. 



++ ++ Lobes of involucr e without scarious margins. 



5. C. cuspidata, Wats. Habit of C. pungcns, 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. pungens; but by the description, it should be very distinct. 

 Sandy hills at San Francisco. 



6. C. Clevelandi, Parry. Prostrate or assurgent, the rather few 

 branches 2 — 3 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- 



