574 
tember 6 (no. 781). This is a well-marked species when growing, 
although somewhat difficult to characterize. It is a much lower 
and more slender plant than G. odtusifolium L., of greener aspect, 
with looser inflorescence and fewer heads. In habitat it is strik- 
ingly different from G. odtusifolium, which, in East Tennessee and 
in the mountains of Kentucky, confines itself to low fields and fal- 
low ground, where introduced weeds are most frequent, while G. 
Helleri is found upon the dry ridges, sometimes even on arid sand- 
stone outcrops, amid a purely indigenous vegetation. 
XANTHIUM SPECIOSUM 0. Sp. 
A stout much-branched leafy annual herb, about 1.5 m. high. 
Stem about 2.5 cm. in diameter just above the tumid base, erect, 
straight below, zigzag above, four-angled, obtusely below, rather 
acutely above, striate above between the prominent angles, hard 
and almost ligneous in texture, with greenish cortex, sparsely 
papillose below with white, rather conspicuous papillae that are 
often extended into short stout appressed antrorse prickle-like 
trichomes, strongly hispidulous above with similar trichomes, in- 
terspersed with minute ones; petioles rather slender, striate, 
deeply grooved on upper face, especially towards the enlarged base, 
strongly hispidulous, minutely pubescent along the groove, the 
lower ones 10-15 cm. long; leaf-blades (the larger ones 17-20 cm. 
long, 19-22 cm. wide) very broadly triangular-ovate, rather deeply 
cordate with a wide rounded sinus which is interrupted by a small 
triangular portion of the blade included between the two primary 
side-veins, rather acute at apex, obtusely and not deeply 3—5-lobed, 
with the primary lobes themselves slightly lobed, obtusely and not 
conspicuously dentate, rather thick, dull green, paler beneath, 
strongly papillose, scabrous on both surfaces, hispidulous along 
the veins and margins, especially beneath, with appressed antrorse 
prickle-like trichomes, rather thickly besprinkled on both surfaces 
with minute shining resinous granules, veins and larger veinlets 
prominent, especially beneath, divergent at a wide angle, the mid- 
nerve and the almost equally strong primary side-veins broad, 
somewhat flattened, strongly striate; flowers not seen; fruiting in- — 
volucres 2.5-4 cm. long, 2.5—3 cm. wide (including prickles), ovoid, 
light brown in color, sparsely besprinkled with shining resinous 
granules, rostrate at apex with two or three very stout, more or 
less incurved, uncinate or biuncinate beaks 10-12 mm. long, 
densely aculeate with long stout strongly uncinate prickles (the 
hook nearly horizontal to very strongly incurved), 8-9 mm. long, 
the lower retrorse, the middle horizontal,the upper antrorse; both _ 
beaks and prickles densely hispid (the former to near the apex, 
