View source for Cirsium eatonii

{{Plant2000
|apex architecture or shape=spiny
|apex orientation=ascending;spreading
|apex position=outer
|apex shape=linear-acicular;entire;plane;spine-tipped
|array architecture=subcapitate;spiciform;racemiform;branched
|base orientation=short-appressed
|blade shape=oblong
|bract shape=spiny-fringed
|branch orientation=ascending
|caudex architecture=taprooted
|collar coloration=stramineous
|collar variability=differentiated
|corolla coloration=ochroleucous;yellow;lavender;pink;purple
|cypsela coloration=brown
|face architecture=winged-petiolate;sessile
|face arrangement=distributed
|face count=present;many
|face external texture=glabrous;villous;glabrous;villous
|face other=principal
|face position=adaxial;basal;cauline;distal
|face size=reduced;reduced
|head architecture=sessile;short-pedunculate
|head arrangement=crowded
|head orientation=erect;nodding
|involucre coloration=green;suffused with dark-c-purple;purple
|involucre external texture=villous;tomentose
|involucre shape=ovoid;campanulate
|involucre width=wider
|lobe arrangement=spaced;spaced
|lobe arrangement or shape=linear
|margin arrangement=overlapping
|margin shape=undulate;unlobed;spiny-dentate;pinnatifid;lance-oblong;triangular;3-lobed;spiny-dentate
|midvein external texture=arachnoid-tomentose
|phyllary size=subequal
|ridge width=narrow
|stem architecture=simple;branched;branched
|stem external texture=glabrous;villous;tomentose;glabrate
|stem internal texture=fleshy
|stem orientation=erect;ascending
|tip position=exserted
|tooth arrangement=spaced
|trichome architecture=septate;septate;septate;septate;non-septate
|trichome external texture=arachnoid-tomentose
|whole organism life style=perennial
}}
Cirsium eatonii is a polymorphic species widely distributed in a high elevation archipelago across the central Rocky Mountains and the Intermountain Region. During Pleistocene glacial episodes, the progenitors of this species complex undoubtedly occupied lower elevation sites and likely had more contiguous populations. Post-glacial isolation of these populations in allopatric high elevation sites has allowed them to differentiate to a greater or lesser extent. Prehistoric or recent introgressive hybridization with other thistle species probably has contributed to the diversification of the complex (R. J. Moore and C. Frankton 1965). Several of the races recognized here as varieties have been treated in the past as species (e.g., C. clokeyi, C. peckii). Their current geographic isolation and more or less distinctive features might support such recognition, but application of this approach across the complex would result in a proliferation of microspecies.
apex architecture or shape	spiny +
apex orientation	ascending + and spreading +
apex position	outer +
apex shape	linear-acicular +, entire +, plane + and spine-tipped +
array architecture	subcapitate +, spiciform +, racemiform + and branched +
base orientation	short-appressed +
blade shape	oblong +
bract shape	spiny-fringed +
branch orientation	ascending +
caudex architecture	taprooted +
collar coloration	stramineous +
collar variability	differentiated +
corolla coloration	ochroleucous +, yellow +, lavender +, pink + and purple +
cypsela coloration	brown +
face architecture	winged-petiolate + and sessile +
face arrangement	distributed +
face count	present + and many +
face external texture	glabrous + and villous +
face other	principal +
face position	adaxial +, basal +, cauline + and distal +
face size	reduced +
head architecture	sessile + and short-pedunculate +
head arrangement	crowded +
head orientation	erect + and nodding +
involucre coloration	green +, suffused with dark-c-purple + and purple +
involucre external texture	villous + and tomentose +
involucre shape	ovoid + and campanulate +
involucre width	wider +
lobe arrangement	spaced +
lobe arrangement or shape	linear +
margin arrangement	overlapping +
margin shape	undulate +, unlobed +, spiny-dentate +, pinnatifid +, lance-oblong +, triangular + and 3-lobed +
midvein external texture	arachnoid-tomentose +
phyllary size	subequal +
ridge width	narrow +
stem architecture	simple + and branched +
stem external texture	glabrous +, villous +, tomentose + and glabrate +
stem internal texture	fleshy +
stem orientation	erect + and ascending +
tip position	exserted +
tooth arrangement	spaced +
trichome architecture	septate + and non-septate +
trichome external texture	arachnoid-tomentose +
whole organism life style	perennial +