HUMULUS AMERICANUS 133 
early to the éxtremity. In the European the summit of the 
leat j is abruptly toothed. In the native plant the male flowers 
les ) ikewi 
acuminate. In some specimens, as in e European plant, the 
upper leaves are simply cordate and enti a in all cases the 
denticulations are smaller and more numero 
Subsequently, however, mall botanists (so far as we know) have 
united this indigenous American hop with H. Lupulus Linn. of 
Europe (cf. A. Gray, Man. Bot. Northern United States, p. 464 
amg bares & Brown, Illust. Fl. Northern United States, 
&e., p. 530 (1896) ; and Index Kewensts). 
n the opinion of the present writers H. americanus Nuttall 
is a distinct species. It can easily be separated from all forms of 
H, Lupulus by its foliage, as Nuttall pointed out; it has, more- 
over, other ae characters. The two species can be con- 
trasted as follow 
H, americanus. H. Lupulus. 
Lobes of leaf. .| 5-11, with tendency | 3-5 (very rarely 7), 
for terminal lobe to terminal lobe not 
Apex oflobes . “| Acuminate use 
Terminal lobe About 3 the length of| 3 = usually id 
the lamina; breadth of lamina; bread 
show b length; hae es aust lnc aie 
rrow, @& ase broader, more 
width of the Tobe a + width of the 
Furrow of petiole . Shallow Usually deep : 
Stipules -.| Reflexed Upright to spreading 
Glands of anthers. Usually 10-20 Less than 10 (rarely 
ore than 10) 
Dise of 3 flower .| Eglandular Usually glandular 
Perianth of 3 flower. Usually sonspiendualy Glands usually 0, or 
ndular ew and scat- 
n H. americanus the lamina of the leaf is almost flat ; 
ZH, Laspiins the recurving of the margin and wrinkling of the leaf 
usually well pronounced. In H. americanus the (lupulin) glands 
n the under side of the leaf are usually numerous, 7. ¢. more than 
fit to the }-in. circle, and are often very numerous, ?.¢. more than 
seventy-five to the 4-in. circle; in H. Lupulus the glands are eae 
few, 7.e. less than fifty to the 4-in. circle, very rarely numerous; 
often very few, a. €. less than twenty-five to the 4-in. circle. si 
seein the Secale ne more ‘‘open”’ than those se ‘A. Sipulas 
the flowers appear to be less crowded together. On close 
scare the U Forence is found to be due to the greater 
esas of the flowering branches of ZH. eee ayn ut: that they 
stand out from the axis (primary, secondary, &e.), bearing them 
more nearly as eet pine coma n H. Lupulus, a i. 
