460 
SYNGENESIA NECESSARIA. 
Nutt. 2. p. 182. 
Tussilago Integrifolia, Mich. 2. p. 121. Willd. Sp. pi. S. p. 1964. 
Perdicium Semiflosculare, Walt. p. 204. 
Root somewhat tuberose, perennial. Leaves oblong, lanceolate, some- 
times obovate, with fine retrorse denticulations, which, in the mature leaf 
are nearly obsolete, green and glabrous on the upper surface, covered with 
a white very dense cottony tomentum underneath. Scapes several from 
each root, six to ten inches long, tomentose, one-flowered; the flowers at 
first nodding, becoming erect as the seed matures. Calyx imbricate. Scales 
linear-lanceolate, appressed, clothed with a ferruginous tomentum, except the 
midrib which is glabrous. Exterior florets of the ray 16 to 20, glabrous, 
white on the interior surface, purple on the outer; just within these is a se- 
cond series of female florets with long styles and only the rudiment of the 
corolla. Florets of the disk sterile, bilabiate, one lip broad, reflexed, 
slightly three-cleft, the other lip deeply two-cleft, with the segments revo- 
lute. Seed of the fertile florets oblong, striate, glabrous. 
Grows in damp pine barrens. 
Flowers March — April. 
SILPHIUM. 
Involucrum foliace- 
um, squarrosum. Se- 
mina compressa, ob- 
cordata, emarginata, 
bidentata. Recepta- 
culum paleaceum.* 
Gen. Pe. 1334. 
Involucrum leafy, 
squarrose. Seeds com- 
pressed, obcordate, e- 
marginate, two-tooth- 
ed. Receptacle chaffy. 
# Gummiferum. E. 
S. caule erecto, hispido, gummi- 
fero; foliis sinuato pinnatifidis, sub- 
tus subhispidis; floribus majusculis, 
axillaribus subsessilibus; involucri 
squamis ovatis, acuminatis, margine 
hispidis. E. 
Stem erect, hispid, bearing gum; 
leaves sinuate, pinnatifid, under- 
neath somewhat hispid; flowers 
large, axillary, nearly sessile; scales 
of the involucrum ovate, acuminate, 
hispid along the margin. 
Root perennial? Stem two to three feet high, robust, very hispid and 
rough, exuding whenever wounded a terebinthine gum, so abundant that it 
sometimes I am told almost encrusts the plant. Leaves sinuate, pinnatifid, 
hispid on the under surface, particularly along the veins, the segments very 
acute, and generally more remote and incised than in the other pinnatifid 
species. Flowers larger than those of any other species in this genus that I 
liave seen, axillary, on short squarrose peduncles. Scales of the involucrum 
