GENUS 104. THISTLE FAMILY. 549 
1. Cirsium lanceolatum (L.) Hill. Common 
Bur or Spear Thistle. Fig. 4636. 
Carduus lanceolatus L. Sp. Pl. 821. 1753. 
Cirsium lanceolatum Hill, Herb. Brit. 1: 80. 1769. 
Cnicus lanceolatus Willd. Prodr. Fl. Berol. 259. 1787. 
Biennial; stem stout, branched, more or less to- 
mentose, 3°-5° high, leafy to the heads. Leaves dark 
green, lanceolate, acuminate, deeply pinnatifid, 3’-6’ | 
long, or the lowest larger, decurrent on the stem and 
branches, the lobes triangular-lanceolate, tipped with 
stout prickles, the margins and decurrent bases 
bristly, the upper surface strigose-pubescent or his- 
pid, the lower brown-tomentose and midnerve pilose, 
especially when young; heads mostly solitary at the 
ends of the branches, 14’-2’ broad, 14’-2’ high; bracts 
of the involucre cottony, narrowly lanceolate, acumi- 
nate, all tipped with slender, erect or ascending 
prickles; flowers dark purple. 
In fields and waste places, Newfoundland to Georgia, 
Minnesota, Nebraska, Oregon and California. Natural- 
ized from Europe. Native also of Asia. Plume-, bank- 
or horse-thistle, bell-, bird-, blue-, button-, boar-, bull- or 
roadside-thistle. July—Nov. 
2. Cirsium altissimum (L.) Spreng. Tall or Roadside Thistle. Fig. 4637. 
Carduuse altissimus L. Sp. Pl. 824. 1753. 
Cnicus altissimus Willd. Sp. Pl. 3: 1671. 1804. 
Cirsium altissimum Spreng. Syst. 3: 373. 1826. 
Biennial or perennial; roots often thickened; 
stem pubescent or tomentose, stout, branched, leafy 
to the heads, 3°-10° high. Leaves ovate-oblong or 
oblong-lanceolate, sessile or slightly clasping, spar- 
ingly pubescent above, densely white-tomentose be- 
neath, scarcely or not at all decurrent, acute, spinu- 
lose-margined, entire, dentate with bristle-pointed 
teeth or lobed, sometimes pinnatifid into oblong or 
triangular-lanceolate segments, the lowest some- 
times 8’ long, narrowed into margined petioles, the 
uppermost linear or lanceolate, much smaller; 
heads about 2’ broad, 13’-2’ high, mostly solitary at 
the ends of the branches; outer bracts of the invo- 
lucre ovate or ovate-lanceolate, firm with a dark, 
slightly glandular spot or band on the beak, tipped 
with short prickles, the inner linear-lanceolate, 
acuminate, unarmed; flowers light purple. 
In fields and thickets, Massachusetts to Ohio, Min- 
nesota, Florida, Nebraska and Texas. Aug.—Sept. 
Cirsium iowénse Pammel, with slightly larger heads 
and longer-tipped inner involucral bracts, appears to 
be a northwestern race of this species. 
3. Cirsium discolor (Muhl.) Spreng. Field 
Thistle. Fig. 4638. 
Cnicus discolor Muhl.; Willd. Sp. Pl. 3: 1670. 1804. 
Carduus discolor Nutt. Gen. 2: 130. 1818. 
Cirsium discolor Spreng. Syst. 3: 373. 1826. 
Similar to the preceding species, but lower and 
more leafy, seldom over 7° high. Leaves deeply pin- 
natifid into linear, linear-lanceolate or falcate, prickly 
toothed segments, white tomentose beneath, sessile. 
the basal ones sometimes 12’ long; heads 13’-2" broad, 
about 13’ high, usually involucrate by the upper 
leaves, mostly solitary at the ends of the branches; 
outer bracts of the involucre coriaceous, ovate, 
slightly woolly, tipped with slender bristles, which 
are longer than those of the preceding species; inner 
bracts lanceolate, acuminate, unarmed; flowers light 
purple or pink, rarely white. 
In fields and along roadsides, New Brunswick to On- 
tario, Georgia, Minnesota, Nebraska and Missouri. July— 
Nov. 
