38 MISSOURI BOTANICAL GARDEN. 
which are observable in much of the form named micro- 
carpa. 
As a rule the prevalent number of leaflets in both of 
these forms seems to be 5, while their number is rarely 
more than 3 in the eastern Pignut, with which, as will be 
seen, the other two forms are likely to be associated east 
of the Alleghenies. The hairy hill form, called villosa, 
not infrequently bears nuts which, separated from husk 
and twig, might easily pass for extreme forms of the 
Mockernut, and I was for a time inclined to consider this 
variety a hybrid with the latter, but this opinion does not 
appear to be substantiated by a fuller knowledge of the 
facts. In the southern Appalachian region are also found 
trees with leaves persistently tomentose until the maturity 
of the fruit, which are deserving of further study. 
+ + Buds large (the terminal 8 to 15 mm. long), ovoid, nearly or quite 
glandless; twigs frequently somewhat tomentose at end, buff, 
gray or brownish, usually much stouter. 
++ Bark not shaggy; outer scales of terminal buds soon deciduous; 
husk of medium thickness, not parted quite to the base; nut 
angular but not much broader than thick. 
7. H. auBa (L.) Britton. Carya tomentosa, Nuttall.— 
The Mockernut.— A medium sized tree; bark gray, rather 
thin, deeply fissured and also checked into minute scales ; 
twigs rather stout, mostly reddish-gray and with conspic- 
uous lenticels, often tomentose;. terminal buds densely 
hairy, broadly ovoid, obtuse to very acute, the outermost 
scales falling in early autumn, exposing the yellowish-gray 
silky inner scales, some of which fall during the winter ; 
lateral buds red-brown, the outer scale often splitting only 
late; fruit one and a half to two and a half inches long, 
depressed globose to pyriform; husk 3 to 4 mm. thick, 
splitting to some distance below the middle; nut brown, 
from globose to narrowly ovoid-oblong, mostly somewhat 
flattened and (often obscurely) angled, usually acute at 
both ends and in the longer forms attenuate above; shell 
about 2 mm. thick and very hard, the commissure firm ; 
