514 COMPOSITAE 
142. CIRSIUM Sis * Adans. Fam, Pl. 2: 116. 1763; emend. DC. 
Prod. 6: 634. 1837. 
Annual, biennial, or perennial, more or less arachnoid-tomentose herbs with posias x or 
stout taproots, the stems of the perennial species arising from the caudex-like wn of 
the taproot or from buds produced on widely spreading, horizontal, rhizome- lik roots. 
Leaves alternate, generally spiny-lobed or -divided, sessile by a petio ole-like or amplexicaul 
base, the base sometimes more or less decurrent along the stem as a spiny wing. a ge 
hairy. Flowers perfect or — wr paree and the plants nearly or quite dioecious ; corollas 
whitish, yellowish, rose, or red and tubular with a slender tube and 5-cleft limb. Achenes 
narrowly obovate or Sites, sapeee ot smooth, the hilum basal. Pappus of numerous 
plumose bristles (or sometimes a few merely barbellulate), these united at the base and 
deciduous in a ring. [Name Eons the Greek, referring to the use of thistles as a remedy 
for swollen veins. ] 
A genus of about 250 species, in the northern hemisphere. Type species, Carduus heterophyllus L. 
For authorship of generic name, see ag —— 8: 278. 195 
e of the reasons for difficulties e ered in treating our native species of Cirsium is ae natural lines 
= a become blurred, if not all bat Cbiiterated dad . Phat 93 hy —— zation. Not only does hybridiza- 
r be pals closely related series} rs between species which wo 
distantly related i sie onde Ea oS prin a Cc. ee rcetoeik ele d08 C. brevifolium and C. utahense, 
cy: Dur rse 0 thistle over i in “field and herbarium, _Sybrigs (suspected or otherwise) have 
becin tute seal sting in hae ington, Or — and mut ornia her 99 the following entities: andrewsiit and 
rcetorum, ee cwsit sat remotifolium Cc . mendocinum Petr:  eeeialbion and foliosum, brevifolium 
tad undulatum, brevifoli and utahense, ae Sr rnicum and cymosum, “calsfornicum var. pierce and foliosum 
a quercetorum _ eek wean cum f. parishii paok). callilepis and querc m (cf. C. amblylepis Petrak), 
callilepis and remotifolium, callilepis var. pseudocarlinoides and cymosum, call epis var. pseudocarlinoides and 
hallit, canovirens and undulatum, canovirens an F eaphense cf. “C. subniveum” of eraeed ee _ 
cymosum, cymosum and pastoris (?), cymosum and proteanum, cymosum and remotifolium, douglastt and quer 
torum, douglasii var. canescens and cymosum, foliosum and undulatum, fontinale and quetcrtos yeh, yes ei 
and proteanum, occidentale and quercetorum, pastoris and proteanum, proteanum and remotifolium. 
In the — wing account of the genus Cirsium on the Pacific Coast, only ree a ™ the 
or immediately pertinent to the accepted name has been given. For further synonymy a many other 
data, see Franz Petrak, cea Pines mcg Arten der Gattung Cirsium (em Bot, Centralbl 35: 223- 567. 
region 
Plants introduced ag ged Old World, either dioecious with unisexual flowers in small heads or monoecious 
perfect flowe medium-sized. heads, if monoecious the oo on of the leaves scabrous or Sis 
Plants dioecious REISS heads commonly numerous, small, 1.5—-2.5 cm. long; leaves pet scabrous-hispid 
. arve 
Siuac maroon biennial; heads medium-sized, mostly 3-4 cm. long; leaves see ‘ispid on the upper 
Pl. e New eho monoecious; upper surface of leaves not scabrous-his 
eae abe pectinate on the margins (rarely the outer piataries Pearle bi in C. callilepis, C. doug- 
lasit, C. hookerian ly and C. nidulum; uppermost spiny-margined leaves sometimes closely subtend 
the head = simulate phyllaries 
Back of at least some of the oliitlecies iene a mare! or spot or ridge. 
cence of stems and | oid. 
Flowers dat i i aay red or ia mine, straight in the head; soncecten perennial from the 
tra Nevada ea ssi 14. C. nidulum., 
vida es lavender, pink, or pial, the outermost in the head spreading. 
lants perennial ep new rosettes arising from horizontal roots; heads medium-sized o 
large, (2 or)3— long; plants “oF . hills and forest borders, chiefly of Oregon 
and Washi 1 tend ee and eastward). 
Stems mostly 1-2 m. tall; heads 3-4 cm. - ng, somewhat constricted above the sub- 
lobose hase; oraee om phyllaries 1-2 mm. long; south: centres Oregon and 
adjacent Californi B.C: ch 
Stems mostly 1 m. tall or less; spines on phyllaries mostly 3- ‘“ mm, .. northern 
Oregon northward and eastward, 
Flowers pink or ila rarely white; leaves wine, yg and below; heads 
4—5 cm. lon undulatum. 
Flowers elon secdia: leaves mostly bicolored, green above Se ll (2 or)3-4.5 
4, evifonw 
ft if sometimes perennial the ne . rosettes co. from 
acoene on the, cigeoer: — leaves sometimes markedly decurrent — 
medium-sized, 2-3.5 cm. long; plants of wet ine chiefly in Califor 
Plants a arachnoid or 2 labrescent, the upper side of the leaves elaros or nearly 
plants of central Calif 7. C. hydrophilum 
Plants pi aa scarcely glabrescent, the upper side of the Sen with per- 
sistent arachnoid tomentum; plants of desert ranges oa — 
m 
Plants mo the —_. like 
s 
small or 
avense. 
of stems and leaves crispy-puberulent as well as arachnoid (the crispy-puberulent t hairs 
are monbea ular. translucent, shining, and often iridescent; sometimes they are quite scant 
and sometimes a: ered by a thick coating of arachnoid tomentum). 
Phyllaries toed & re except for the erect or spreading chartaceous tip (i.e., 
all o —— all mech the herbaceous part of the metiare at Pct A nga os spot on phyl- 
Spine at bie Sat ok bares widely spreading, mostly 3-5 mm. long; taprooted, monocarpic 
a a ennial plants of wet places from southern Oregon yap Raat to central Californ 
