474 COMPOSITE. 



1. 0. Calcitrapa, Linn. Sp. PI. ii. 917 (1753). Stoutisb, rigid, 1—2 

 ft. high, very widely branching, leaves narrow, laciniate-pinnatifid: the 

 uppermost somewhat involucrate-crowded about the sessile head: prin- 

 cipal bracts of the involucre armed with a widely spreading long and 

 rigid subulate spine, which bears 2 or 3 spinules on each side at base: 

 corollas red-purple: pappus none. — Common along roadsides at and~ 

 near Vacaville. 



2. C. Melitensis, Linn. 1. c. Erect, 2—4 ft. high, cinereous-pubes- 

 cent, or when young slightly woolly: radical leaves lyrate-pinuatifid; 

 cauline lanceolate, mostly entire, narrowly deciirrent: principal bracts of 

 involucre with a slender spine of about their own length which is 

 pectinate-spinulose at base; innermost with spinescent tips: flowers 

 yellow: pappus of very unequal rather rigid bristles or squamellate. — A 

 very common field and wayside weed. 



3. C. solstitiatjIS, Linn. 1. c. Erect, 1 — 2 ft. high, canescent with 

 cottony wool: radical leaves lyrate-pinnatifld; cauline lanceolate and 

 linear, mostly entire, decurrent on the branches in narrow wings: heads 

 pedunculate: middle bracts of the involucre with a long rigid spreading 

 spine several times their own length, and having 1 or 2 spinules at base; 

 outermost bearing a few small palmate prickles; innermost only scarious- 

 tipped: corollas yellow: pappus double; outer of short and squamellate, 

 inner of longer bristles. — Very common in Napa Valley, and sandy fields 

 along the San Joaquin. 



108. CNICTJS, Vaillant. Annual with sinuate-pinnatifld leaves thin- 

 nish and reticulate-veiny, only weakly prickly. Heads enclosed within 

 large leafy accessory bracts. Proper bracts of the involucre thin- 

 coriaceous, in few ranks, many or all of them abruptly tipped with an 

 aristiform or spinescent and pectinate-prickly appendage. Receptacle 

 densely setose with long and soft bristles. Achenes terete, strongly 

 many-striate, the corneous margin at summit 10-toothed. Pappus 

 double; each set consisting of 10 aristiform bristles; the outer set longer 

 and naked, the inner short and fimbriolate. 



1. C. BENEDiCTUS, Linn. Sp. PI. ii. 826(1753). (Blessed Thistle.) 

 A less rigidly thistle-like annual, with pale yellow flowers in large leafy- 

 iuvtslucrate heads; occurring rarely as a ballast waif at San Francisco, 

 but plentiful in fields along the Sacramento River above Sacramento. 



109. CENTROPHYLLUM, Necker. Annual or biennial. Leaves 

 amplexicaul, reticulate-veiny, rigid, pinnatifid, and spinescent. Outer 

 bracts of involucre foliaceous, with few spinescent lobes; the inner 



