G^RTNBRIA COMPOSITiE 337 



XANTHIUU 



Nutt. stems 1-3 feet high, from an annual or biennial root, diffaBe1> 

 branched from the base, birBute-pubescent or hispid, sometimes canescent 

 with strigoae-sericeous pubescence when young : leaves of ovate or round- 

 ish outline, 1-3 inches broad bipinnatifid or the upper oblong and only 

 pinnatifld: staminate recemes solitary or paniculate: pistillate involucres 

 armed with flat and thin lanceolate-subulate smooth and glabrous long 

 and straight spines S-4 lines long, commonly 1-flowered. On sandy plains 

 and river-banks, Brit. Columbia to California and Nevada. 



6. bipinnatiflda 0. Ktz. Eev. Gen. i, 339. Franseria bidinnatifida Nutt- 

 Herbaceous perennial with stout procumbent stems 2-3 feet long, some- 

 what hirsute : leaves ovate in outline 1-2 inches long, 2-3 pinnately parted 

 into oblong-linear divisions and small oblong lobes, canescent with soft 

 tomentum or fine hirsute-sericeous pubescence : staminate heads rather 

 large, in dense spikes or racemes; pistillate beads ovate fusiform, armed 

 with rather short and thick but flattish tubercle-like spines, their acute 

 tips sometimes incurving. On sandy beaches along the coast, Brit. Colum- 

 bia to California. 



6. Chamissonis 0. Ktz, 1. c. Franseria Chamissonis Less. Stems pro- 

 cumbent, 2-3 feet long, from a perennial root; leaves cuneate-obovate or 

 oblong-ovate with a cunpate base, 3-5-nerved at base, obtusely serrate, the 

 lower often laciniate-incised : staminate spikes or racemes dense, of rather 

 large heads ; pistillate heads ovate, armed with rather short and thick but 

 flattish canaliculate tubercule-like spines. Sandy sea-beaches, Brit. Co- 

 lumbia to California. Not common. 



* * Involucre of the staminate heads of few distinct bracts. Re- 

 ceptacle cylindraceous. 



XANTHIUM Tourn. L. Gen. n. 1056. (cocKLB-Bua) 

 Coarse annuals with branching stems, alternate and usually 

 lobed or toothed leaves, and most clustered heads of .greenish 

 or yellowish flowers, in terminal or larger axillary clusters of 

 both sexes, the staminate uppermost. Involucre of the globu- 

 lar sterile heads 1-2 series of small narrow bracts. Receptacle 

 distinctly paleaceous, a cuneate or linear-spatulate chaffy bract 

 partly enclosing each steaile flower. Filaments monadelphous. 

 Anthers distinct but connivent, the inflexed apical appendage 

 mucronate. Sterile style unappendaged. Fertile head a closed 

 and ovoid bur-like 2-celled and 2-flowered involucre, 1-2-beak- 

 ed at the apex, the surface clothed with uncinate-tipped prickles: 

 each flower a single pistil, maturing a thick ovoid achene, the 

 two permanently enclosed in the indurated prickly involucre. 



* Leaves cordate or ovate, 3-ribbed from the base, with dentate 

 margins, and often incised or lobed, on long petioles: axils unarmed: 

 fruiting involucre with 2 prominent beaks. 



X. STRCMAEiUM L. Sp. 987, Rough : stems 1-6 feet high : leaves slender- 

 petioled, broadly ovate to orbicular, 3-ribbed and more or less cordate at 

 base, the lower often 10 fnches broad, irregularly dontate and more or 

 less 2-B-lobed ; fruiting involucre 6-9 lines long, glabrous or puberulent ; 

 the beaks straight and rarely at all hooked at maturity. In waste places. 

 Naturalized from Europe. 



X. Candense Mill. Diet. ed. 8, No. 2. Stems stout, 1-2 feet high, often 

 punctate with brown spots : leaves ample, broadly ovate, coarsely and irreg- 



