Cirsium helenioides
Cirsium rydbergii
melancholy thistle
alcove thistle, Rydberg's thistle
single, erect, ± arachnoid-tomentose;
branches 0 or few, ascending.
1–several, erect or ascending to lax and hanging, glabrous or thinly tomentose;
branches 0–few, ascending.
oblong to broadly lanceolate, 20–40 × 4–8 cm, finely spinulose-dentate or proximal cauline pinnatifid, lobes undivided, finely spinulose-dentate, main spines 1–2 mm, abaxial faces white-tomentose (with non-septate trichomes), adaxial glabrous;
basal present at flowering, petiolate, bases tapered;
cauline sessile, reduced distally, bases clasping, not decurrent;
distal (few, well separated), oblong or linear, the uppermost reduced to linear bracts.
blades elliptic, 30–90+ × 10–40 cm, 1–2 times pinnately lobed, lobes linear to ovate, strongly undulate, main spines slender, 5–15 mm, faces often glaucous, glabrous or thinly tomentose and soon glabrescent;
basal present at flowering, petiolate or winged-petiolate;
proximal cauline winged-petiolate;
mid sessile, much reduced, less deeply lobed, bases clasping, short-decurrent 0–2 cm;
distal linear or lanceolate, bractlike, very spiny.
2–10(–30) cm (elevated above distal leaves).
0.5–6 cm.
broadly ovoid, 2–3 × 2–3.5 cm, glabrous or loosely arachnoid.
hemispheric, 1.4–2 × 1–2 cm, phyllary margins thinly tomentose or glabrate.
red-purple, 25–30 mm, tubes 10–23 mm, throats 8–14 mm (noticeably wider than tubes), lobes 7–10 mm;
style tips 4–5 mm.
dull white to pink or purple, 16–20 mm, tubes 7–8.5 mm, throats 4–6.5 mm, lobes 4.5–6 mm;
style tips 2.5 mm.
in 8–10 series, imbricate, green, ovate or lanceolate (outer) to linear-lanceolate (inner), abaxial faces with a prominent elongate glutinous ridge, outer and middle tightly appressed, margins entire, apices with ascending, weak spines 0–1 mm;
apices of inner phyllaries attenuate, flat.
in 5–8 series, strongly imbricate, (green, drying green or light brown), ovate to lance-oblong, abaxial faces with or without poorly developed glutinous ridge;
outer and mid bases appressed, margins entire, not scabridulous-ciliolate, apices spreading or reflexed, green to brownish, lance-ovate, elongate, flattened, spines slender, 3–25 mm;
apices of inner straight, entire.
borne singly or less commonly 2–5 in terminal clusters.
few–many, erect or nodding in clusters at tips of distal branches in paniculiform arrays, not closely subtended by clustered leafy bracts.
light brown, 3–5 mm, bodies and apical collars concolorous;
pappi 20–30 mm.
gray or brown, 3.7–4.5 mm, apical collars not differentiated;
pappi 10–15 mm.
= 34.
= 34.
Cirsium helenioides
Cirsium rydbergii
Cirsium helenioides is one of only two species of the genus that have native populations in the Old World and the flora area. Neither reaches the North American mainland.
The conservation status of Cirsium helenioides is not known; it is known in the flora area only from a single fjord and possibly should be considered of conservation concern.
of conservation concern
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Cirsium rydbergii is endemic to the Colorado Plateau of northern Arizona and southeastern Utah.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
WildflowerSearch
iNaturalist
USDA Plants Database
