700 COMPOSITAE 
Flowers yellow 
1. C. spinosissimus, Walt. (Fig. 2, pl. 197.) YEtLow TuHISTLE. 
(Cirsium spinosissimum, (Walt.) Scop.) Stem quite stout, 1 to 5 ft. 
high, woolly when young. Leaves in general outline lance-shaped, the up- 
per ones clasping the stem, margins deeply lobed and with strong prickles 
at angles of the lobes. Heads 2 to 4 in. broad, the involucre bracts long, 
lance-shaped, with prickles at the margins. Flowers yellow. Mostly in 
moist soil. May-Aug. 
Flowers purple, pink or white 
2. C.lanceolatus, L. (Fig. 2, pl. 198.) Common SpEAR THISTLE. 
(Cirsium lanceolatum, (L.) Hill.) Stem branched, 3 to 5 ft. high, more 
or less white woolly but not prickly or only moderately so. Leaves lance- 
shaped, divided into triangular lobes each side of mid-vein, the lobes with 
prickly margins, at base the leaf is decurrent on the stem. All the bracts 
of the egg-shaped involucre terminate as prickles. Common. Fields and 
waste places. June-Noy, 
3. C. altissimus, L. (Fig. 3, pl. 197.) Tati Tuistir. (Cirsium 
altissimum, (L.) Spreng.) Stem not very stout, somewhat branched, the 
branches usually ascending, downy or woolly. Leaves lance-shaped, the 
margins toothed or rather deeply lobed but not divided into narrow seg- 
ments, prickly at borders. Outer bracts of the involucre terminating as 
prickles, the inner bracts not prickly. Fields, thickets, along fences. 
Aug.-Sept. 
4. C. discolor, (Muhl.) Nutt. Firrp Tuistre. (Cirsium discolor, 
(Muhl.) Spreng.) Tall and somewhat slender, 2 to 7 ft. high. Heads as 
in No. 3. Leaves white woolly beneath, deeply divided into lance-shaped 
segments, the borders of which are prickly. Fields and roadsides. July- 
Nov. 
5. C. odoratus, (Muhl.) Porter. (Fig. 3, pl. 198.) FRAGRANT 
THISTLE. PASTURE THISTLE. (Cirsium pumilum, (Nutt.) Spreng.) Stem 
low, stout, 1 to 3 ft. high. Leaves green on both sides, lance-shaped, cut 
into angular lobes with stout prickles. Outer bracts prickly, inner un- 
armed. This fragrant thistle has much of the time during its season of 
flowering, a number of butterflies balancing on the purple flowers. 
6. C. muticus, (Michx.) Pers. (Fig. 1, pl. 197.) Swamp THISTLE. 
(Cirsium muticum, Michx.) Stem rather slender, 3 to 8 ft. high, angled, 
branching above. Branches with only a few small leaves and terminated 
by one or more heads, Leaves lance-shaped, entire or deeply lobed on 
each side (pinnatifid) and densely white woolly beneath, lower 4 to 8 in, 
long, borders prickly. Heads about 13 in. broad. Bracts of the involucre 
not prickly. Swamps and moist soil. July-Oct. 
7. C. arvensis, (L.) Robs. (Fig. 1, pl. 198.) CANnapA THISTLE. 
(Cirsium arvense, (L.) Seop.) Perennial, slender, 1 to 3 ft. high. Stem 
striped, smooth. Leaves lance-shaped, deeply lobed, the margins of the 
lobes beset with strong prickles; green on both sides, the lower 5 to 8 in. 
long Heads about 1 in. broad and about as high, flowers rose purple, 
bracts not prickly. Very common in cultivated fields, roadsides, ete. 
June-Sept. 
