SYNGENES1A NECESSARIA. 463 
rather obtuse, slightly fringed. Florets of the ray scarcely exceeding twelve, 
nearly an inch long. 
I suspect that some genuine species among the sinuate-leaved Silphiums 
are yet undefined. 
Grows in dry pine barrens. 
Flowers May— August. 
E 
4. Terbinthinaceum. 
5. caule laevi; foliis 
radicalibus amplis, ro- 
tundato vel reniformi- 
cordatis, sublobatis, 
dentatisque, caulinis al- 
ternis, ovatis, serratis, 
scabris; panicula com- 
posita, multiflora. 
Lin. 
Stem smooth; leaves 
of the root large round 
or reniform, cordate, 
slightly lobed and 
toothed, of the stem 
alternate, ovate, ser- 
rate, scabrous; panicle 
compound, many flow- 
ered. 
Sp. pi. 3. p. 2331. Mich. 2. p. 145. Pursh, 2. p. 577* Nutt. 2. p. 
182. 
Stem erect, four to five feet high, glabrous. Root leaves deeply cordate, 
oblong or round, toothed, when luxuriant slightly lobed along the margin. 
Floivers more numerous than usual in this genus, in large scattered corym- 
bose panicles. Scales of the involucrum nearly ovate, the exterior rather 
acute, the interior generally obtuse. Florets of the ray ten to twelve, about 
an inch long. 
This species appears subject to some variations. In specimens sent me 
by Dr. Schweinitz from Salem, North-Carolina, the root leaves were nearly 
reniform, simply toothed and very scabrous underneath. In specimens col- 
lected in the western districts of Georgia and Alabama, where it appears 
to be more luxuriant, the leaves were lobed and angled, and nearly glabrous 
underneath. In the flowers I can perceive no difference. 
Grows along the mountains. 
Flowers July — August. 
