243 
transversely-wrinkled achenes, and short pappus of numerous rough 
separate and deciduous bristles. 
1, A. Lappa L. Stout, 3 to9 dm. high: leaves roundish or ovate and mostly cor- 
date, or lanceolate with cuneate base, smooth above, somewhat floccose-tomentose 
beneath, mostly sinuate-denticulate. (Lappa officinalis All.)—A common European 
weed of waste or manured ground. 
112. CNICUS Tourn. (Common or PLUMED THISTLE.) 
Mostly biennial herbs, with sessile alternate often pinnatifid and 
prickly leaves, usually large terminal heads of reddish-purple (rarely 
white or yellowish) flowers (which are all tubular, perfect and similar, 
rarely imperfectly dicecious), ovoid or spherical involucre of bracts im- 
bricated in many rows and tipped with a point or prickle, receptacle 
thickly clothed with soft bristles or hairs, oblong flattish (not ribbed) 
achenes, and pappus of numerous bristles united into a ring at base, 
plumose to the middle and deciduous. (Mostly known formerly as 
Cirsium.) 
*“ Heads leafy-bracteate at base: proper bracts of the involucre not prickly. 
1, C. horridulus Pursh. Stem stout, webby-haired when young, 3 to 9 dm, high: 
leaves partly clasping, green, soon smooth, lanceolate, pinnatifid, the short toothed 
and cut lobes very spiny with yellowish prickles: heads 2.5 to 3.5 em. broad, sur- 
rounded by leaf-like and very prickly bracts, which usually equal the narrow in- 
volucral bracts: flowers pale yellow or purple.—Sandy or gravelly soil, near the 
coast. 
** Scales appressed, the inner not at all prickly. 
+ Leaves white-woolly beneath, and sometimes also above: outer involucral bracts succes- 
sively shorter, and tipped with short prickles. 
++ Principal involucral bracts with more or less rigid and pungent prickles : leaves mostly 
persistently tomentose above as well as below. 
2. C. ochrocentrus Gray. Often tall, from 3 to 9 dm, or even 18 to 25 dm. high: 
leaves commonly but not always deeply pinnatifid and armed with long yellowish 
prickles: heads 2.5 to 5 cm. high: involucral bracts rather broad and flat, the viscid 
line on the back narrow or not rarely obsolete, tipped with a prominent spreading 
yellowish prickle: corolla purple, rarely white.—Plains of western Texas. 
3. C. undulatus Gray. Usually lower, 3 to 9 dm. high: leaves rarely pinnately 
parted, moderately prickly: heads mostly 3.5 em. high: principal involucral bracts 
mostly thickened on the back by the broader glandular-viscid ridge, smaller and nar- 
rower, and tipped with an evident spreading short prickle: corollas rose-color, pur- 
ple or white.—A variable species of the northern plains, represented in Texas by the 
var. MEGACEPHALUS Gray, which is a stouter usually broader-leaved form, with 
broad heads 5 cm. or more high. 
++ ++ Involucral bracts tipped with weak bristle-like prickles, or sometimes hardly any : 
upper leaf face soon glabrate and green. 
4. C.altissimus Willd. Stem downy, branching, 9 to 30 dm. high, leafy quite to 
the heads: leaves roughish-hairy above, whitened with close wool beneath, oblong- 
ovate to narrowly lanceolate, undivided, sinuate-toothed, undulate-pinnatifid, or 
twice pinnatifid, the lobes or teeth weakly prickly: flowers chiefly purple,—Borders 
of woods and open ground, common in the Atlantic States and extending into Texas, 
On the prairies and in the live-oak thickets is found var, FILIPENDULUS Gray, which 
is smaller (6 to 9 din. high), with tuberiferous roots, mostly deeply pinnatifid leaves, 
18430—No. 2 7 
