ains.

Southern Ontario.

Maine,--young trees in the southern sections said to have been
produced from self-sown seed (M. L. Fernald); New Hampshire and
Vermont,--introduced; Massachusetts,--occasional; Rhode
Island,--introduced and fully at home (J. F. Collins); Connecticut,--not
reported. Probably sparingly naturalized in many other places in New
England.

Spreading by seed southward; indigenous along the western slopes of
the Alleghanies in Pennsylvania; south to Georgia and Alabama; west
from western New York through southern Ontario (Canada) and
Michigan to Nebraska, Kansas, Indian territory, and Texas.

=Habit.=--A medium-sized tree, reaching a height of 40-60 feet and a
trunk diameter of 1-3 feet; becoming a tree of the first magnitude in
the river bottoms of Ohio, Kentucky, and Tennessee; trunk dark and
straight, the upper branches going off at an acute angle, the lower
often horizontal, both trunk and larger branches armed above the axils
with stout, sharp-pointed, simple, three-pronged or numerously branched
thorns, sometimes clustered in forbidding tangles a foot or two in
length; head wide-spreading, very open, rounded or flattish, with
extremely delicate, fern-like foliage lying in graceful planes or
masses; pods flat and pendent, conspicuous in autumn.

=Bark.=--Trunk and larger branches a sombre iron gray, deepening on old
trees almost to black; yellowish-brown in second year's growth; season's
shoots green, marked with short buff, longitudinal lines; branchlets
rough-dotted.

=Winter Buds and Leaves.=--Winter buds minute, in clusters of three or
four, the upper the largest. Leaves compound, once to twice pinnate,
both forms often in the same leaf, alternate, 6 inches to 1 foot long,
rachis abruptly enlarged at base and covering the winter buds: leaflets
18-28, 3/4-1-1/4 inches long, about one-third as wide, yellowish-green
when unfolding, turning to dark green above, slightly lighter beneath,
yellow in autumn; outline lanceolate, oblong to oval, obscurely
crenulate-serrate; apex obtuse, scarcely mucronate; base mostly rounded;
leafstalks and leaves downy, especially when young.

=Inflorescence.=--Early June. From lateral or terminal buds on the old
wood, in slender, pendent, greenish racemes scarcely distinguishable
among the young leaves; sterile and fertile flowers on different trees
or on the same tree and even in the same cluster; calyx somewhat
campanulate, 3-5-clef