THE WILLOWS OF OHIO. 301 
of its leaves contrasting strongly with the rich green of the upper 
surface. In some hybrids, however, most noteworthily Salix 
candida x. S. petiolaris the resemblance is so close as to make it 
all but impossible to separate the two. But such hybrids usually 
have a distant scolloped serration derived from S. fetiolaris 
which is different from any form of S. humilis. At flowering 
time there will be no difficulty in separating them. 
Salix humilis var. tristis (Ait.) Dwarf Gray Willow. 
A depauperate form of S. humulis with which it is connected 
by many intermediates. It may be described as smaller and 
hairier throughout. It is quite low (to 6 dm.) with smaller 
leaves (to 5 cm. long) more strongly gray tomentose, and catkins 
sometimes scarcely 5mm. long. This can hardly be regarded as 
a distinct. species. There is not a single constant character by 
which the two differ and what differences there are, are such as 
would be likely to be caused by differences in environment. 
Such forms should be considered as varieties rather than as 
species. 
SERICEAE. 
Swamp shrubs, leaves narrowly elliptic-lanceolate, com- 
monly tapering to both ends, serrate with blunt cartilaginous 
teeth to entire, glabrous to glaucous, sericeate below when young, 
generally blackening in drying. Aments born before the leaves, 
sessile or short peduncled, scales darkened at the tip, pilose, 
capsules pedicelled, silvery sericeate at least when young. 
Key. 
From leaves. 
Leaves dull above, silvery silky beneath at least until very 
old, scarcely glaucous. S. sericea. 
Leaves shining above, glabrous on both sides except when 
young, pubescence on young leaves mostly ferruginous, 
quite glaucous below. S. petiolarts. 
From flowers. 
Fruiting catkins dense, sessile, capsule ovoid-conic, obtuse, 
short pedicelled, sericeate even when ripe, hardly 4 mm. 
long. S. sericea’ 
Fruiting caktins, looser, short peduncled, capsule becoming 
cylindric conic, acutish, long pedicelled, nearly glabrous 
when mature, more than 4 mm: long. S. petiolarts. 
Plate XI. Salix sericea. 
Typical leaves flowers and fruit; natural size; ripe capsule drawn in 
with camera lucida, enlarged five times. 
