162 DR. R. R. GATES: A STUDY OF NORTH AMERICAN 
Melanthium is closely related to Zigadenus, which it resembles in having 
the perianth-segments clawed, with two glands at the base of the blade, but 
the glands in Melanthiwm tend to be confluent. The two genera also 
resemble each other in foliage and in inflorescence, but Zigadenus is glabrous 
while Melanthium is characteristically seabrous-pubescent. As regards the 
stamens, they are free from the perianth-segments and about equalling them 
in length in Zigadenus, while in Melanthium they are shorter than the 
segments to which they are adnate. The seeds of the former are oblong or 
linear, while those of the latter are flat and broadly winged. The capsules 
also show characteristic differences. Thus in Melanthium they are truncate 
at the top, while in Zigadenus they are more gradually narrowed and pulled 
out, as it were, at the points where the stigmas protrude. Another difference 
is found in the flowers, which are moncecious in Melanthium, hermaphrodite 
in Zigadenus. 
The differences between the three species of Melanthium are typical specific 
differences, and there is no direct evidence as to how they came about. The 
genus is closely related to Zigadenus on the one hand, and through 
V. parviflorum to Veratrum on the other hand. The scabrous pubescence 
of Melanthium may be supposed to have originated suddenly in a Zigadenus- 
like ancestor. ‘The differences in relative stamen-length and in the adnation 
of the stamens to the petals are no greater than in the species of, e. g., 
Trillium. Hence it is unnecessary to suppose any greater amount of 
extinction between these three genera than occurs between species of the 
sume genus. 
The resemblances and differences between Melanthium and Veratrum are 
pointed out in the following table. The two genera agree in certain features, 
such as the pubescence and the shape of ilie seeds, in which they are con- 
trasted with Zigadenus. On the other hand, Melanthium and Zigadenus are 
closely similar in the glands on the perianth, which in Veratrum have been 
almost completely lost :— 
Melanthium. 
Stem and inflorescence scabrous-pubescent. 
Leaves narrow, sheathing. 
Flowers greenish, white or cream-colored ; 
moneecious or polygamous; on slender 
pedicels; in large terminal panicles. 
Perianth-segments clawed, with 2 more or 
less confluent elands at base, mostly free 
from the ovary. 
Stamens shorter than the perianth-segments 
and adnate to them. 
Seeds very flat, broadly winged. 
Veratrum. 
Rootstocks poisonous. 
Stem and inflorescence pubescent. 
Leaves broad, clasping, strongly veined. 
Flowers greenish, yellowish, or purple, 
rather large; moncecious or polygamous ; 
on short stout pedicels ; in large terminal 
panicles. 
Perianth-segments not clawed, glandless or 
nearly so, sometimes adnate to the base 
of the ovary. 
Stamens shorter than the perianth-segments 
and free from them. 
Seeds very flat, broadly winged. 
