440 COMPOSITE. Senecio. 



and slender subulate bracteoles ; the scales (15-20) narrowly linear, acute ; 

 rays about 8, small ; the disk-flowers 40-50 ; achenia striate, nearly g\a- 

 hroas.—Nutt. ! gen. 2. p. 165 ; DC. prodr. 6. p. 432. 



(3. cauline leaves very small, except those near the base of the stem, 

 which appears scapiform ; heads very few. — S. integerrimus, Nutt. ! in 

 trans. Amer. phil. soc. I. c. p. 411. 



Upper Missouri, Nultall, Mr. Nicollet ! /?. Plains of the Platte towards 

 the Rocky Mountains, Nuttall! May-June. — Stem 12-18 inches high. 

 Radical leaves 3-5 inches long, and 1-2 wide. Heads 6-20, rather large: 

 the calyculate bracts nearly equalling the involucre. 



15. S. hydrophiius (Nutt.) : very glabrous ; stem simple, terete, striate, 

 rather leafy ; leaves (thickish) lanceolate, acute, entire (or obsoletely repand- 

 denriculate), furnished with a prominent midrib ; the radical and lowest 

 cauline elongated, tapering into thickish somewhat clasping petioles ; the 

 others sessile, partly clasping; heads (small) numerous, in a compound naked 

 corymb; the pedicels and involucre scarcely bracteolate; scales of the cyliiT- 

 draceous-campanulate involucre about 8, oblong-linear, obtuse, the tips 

 purplish and somewhat sphacelate ; rays 3-6, very small ; the disk-flowers 

 18-25 ; achenia glabrous, obscurely angled. 



a. stem stout ; the corymbs (not fully developed) thyrsoid-paniculate. — 

 S. hydrophiius, Nutt. ! in trans. Amer. phil. soc. I. c. 



j3. stem slightly striate ; corymbs fasligiate. 



Margin of ponds, &c., in the Rocky Mountains along Ham's Fork of the 

 Colorado of the West, Nuttall! l3. Borders of a lake in the Wind River 

 Chain of the Rocky Mountains, Lieut. Fremont ! Aug. — About 2 feet high. 

 Leaves much like those of Solidago sempervirens : the upper small and 

 scattered. Bracteoles few and very minute. — Heads smaller than in S. 

 integerrimus. Achenia not striate. Receptacle alveolate. 



16. S. lanceolatus : glabrous (except the base of the stem, which is pubes- 

 cent) ; stem tall, virgate, angled, simple or somewhat branched above, very 

 leafy to the summit; cauline leaves uniform (thin), lanceolate, entire, acute 

 at both ends, subsessile (the lowest petioled?); corymbs small and loose, 

 terminal and from the axils of the upper leaves, paniculate; the slender 

 peduncles and pedicels and the small heads sparingly bracteolate; bracteoles 

 filiform-setaceous; scales of the cylindrical 15-20-flowered involucre 8-12, 

 narrowly linear, acuminate; rays few and small; achenia (not striate?) 

 glabrous. 



Along the North Fork of the Platte, Lieut. Fremont! — Stem 3 feet high, 

 slender, inclined to branch from the axils of the upper leaves, terminated by 

 a narrow corymbose panicle. Lower cauline leaves wanting; the upper 

 much longer than the internodes, 4-5 inches long, one-half to three-fourths 

 of an inch wide, mucronulate ; the margin somewhat revolute. Heads 

 about as large as in S. Sarracenicus ; and the attenuated bracteoles 

 similar. Rays a little exceeding the disk. Pappus about the length of the 

 corolla. 



17. S. ampullaceus (Hook.) : very glabrous ; stem grooved, branched 

 •above ; leaves fleshy, oblong, obtuse, entire or denticulate, partly clasping by 

 a cordate base ; the lowest spatulate ; panicle corymbose ; the peduncles in 

 fruit much incrassated and turbinate at the base of the heads ; involucre with 

 a few minute setaceous bracteoles ; rays 7-9, spreading ; achenia slender, 

 strigose-canescent. — Hook. hot. mag. t. 3487; DC. prodr. 6. p. 428. 



Texas, Drummond! — Plant 2-3 feet high. Involucre at first cylindrical, 

 at length enlarged at the base, as in Sonchus, about 20-30-flowered. The 

 short strigose liairs of the achenia promptly emit long spiral threads when 

 moistened. 



