* 
356 LXXV. COMPOSITA. CisiuM. 
having earth heaped up around it, and then the petioles become tender, crisp, 
eatable, like celery. Aug. Sept.t 
69. CIRSIUM. Tourn. 
Gr. kteoos, a swelling of the veins, which this plant was supposed to heal. 
Heads discoid, homogamous ; involucre subglobose, of many rows 
of spinose-pointed, imbricated scales ; receptacle bristly ; style scarce- 
ly divided ; pappus copious, plumose ; achenia compressed, smooth.— 
Herbs with alternate leaves, generally armed with spinose prickles. F's. 
cyanie. 
1. C. arvense. Scop. (Cnicus arvensis. Ph.) Canada Thistle. 
Lws. sessile, pinnatifid, spinous; st. panicled; imvol. round or ovate, with 
minute spines, scales close-pressed, ovate-lanceolate.—2| A very common this- 
tle in fields, roadsides and waste places, N. Eng. to Ohio. It is one of the 
severest pests of the farmer, requiring his constant vigilance to extirpate it from 
his fields. In England it is called cursed thistle. Root creeping, very long and 
exceedingly tenacious of life. Stem 3f high, with a branching panicle at top. 
Leaves alternate, thickly beset with thorns. Heads rather small, purple, the 
involucre nearly thornless, and is the only part of the plant that can be safely 
handled. July. § 
2. C. piscéLor. Spreng. (Cnicus discolor. Muhl.) Tall Thistle. 
Las. sessile, pinnatifid, rough-haired, downy beneath, the segments 2-lobed, 
divaricate, spinose ; invel. globose, the scales ovate, appressed, with spreading 
spines at the tips——@) A slender thistle, 3—5f high, much branched, and leafy 
at the summit. Found in thickets, N. Eng. to Ill. Heads terminating the 
branches, an inch in diameter, with reddish-purple corollas. July, Aug. 
3. C. muticum. Michx. (Cnicus glutinosus. Bw.) Glutinous Thistle. 
Iws. pinnatifid with divaricate segments; invol. ovate, with unarmed, 
villous-arachnoid, glutinous scales.—@) A fine looking thistle found in damp 
soils, Can. and U.S. Stem branching, 3—7fhigh. Leaves armed with spines 
at each angle. Heads 3’ diam., with deep purple corollas, the scales webbed 
and glutinous on the back. Aug. Sept. 
4. C. norripULum. Michx. (Cnicus horridulus. Linn.) Yellow Thistle. 
Lws. sessile, pinnatifid, acutely cut, spinose ; Ads. invested with an exter- 
nal involucre of about 20 very spinose bracts; scales unarmed.—@) Found in 
meadows and hills, N. Eng. to Flor. The stem is 1—3f high, invested with 
wool. Leaves somewhat clasping, woolly and hairy, armed with stiff spines. 
Heads large, with yellowish-white corollas surrounded by a whorl of lanceolate 
or linear leaflets tipped with stiff thorns, the scales webbed. Aug. 
5. C. pumitum. Spreng. (Cnicus odoratus. Muhl.) Pasture Thistle. 
Hairy; /vs. green on both sides, clasping, oblong-lanceolate, pinnatifid, 
the segments irregularly lobed, ciliate, spinose; zmvol. round-ovate, spinose, 
naked.—@) A common, low, turgid thistle in roadsides, pastures, N. Eng. and 
Mid. States. Stem 1—2f high, stout, striate, with 1—3 very large heads of 
fragrant, purple flowers. Aug. 
» 6. C. LANCEOLATUM. Scop. (Cnicus. Ph. Carduus. Linn.) Common Thistle. 
' Iws. decurrent, pinnatifid, hispid, the segments divaricate and spinose; 
wvol. ovate, villous; scales lanceolate; spreading.—@) Common in borders of 
fields, roadsides, N. Eng. and Mid. States, always distinguished by the decur- 
“rent leaves. Stem 3—4f high, winged by the decurrent leaves which are white 
and woolly beneath, armed with formidable spines at all points. Fils. numerous, 
large, purple. Involucre scales webbed, each ending in a spine. July—Sept. 
7. C. aLTissimuM. Spreng. (Carduus. Linn. Cnicus. Willd. 
Tall, branched, villose-pubescent, leafy; Jvs. whitish beneath, spinose- 
ciliate, sessile, lanceolate-oblong, sinuate-dentate, lower ones pinnatifid, petio- 
late ; lobes or teeth spinescent ; invol. ovoid-oblong ; scales close-compressed, ovate- 
lanceolate, outer ones with a spreading spine at apex.—Fields and barrens, 
Penn. and Western States! common. Stem 3—8f high. Leaves 6—8’ by 1—’. 
