Cirsium rydbergii Petr.

Rydberg's thistle (en)

Species

Angiosperms > Asterales > Asteraceae > Cirsium

Characteristics

Perennials, 100–300 cm; caudices and taproots, spreading by creeping roots. Stems 1–several, erect or ascending to lax and hanging, glabrous or thinly tomentose; branches 0–few, ascending. Leaves: 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. Heads few–many, erect or nodding in clusters at tips of distal branches in paniculiform arrays, not closely subtended by clustered leafy bracts. Peduncles 0.5–6 cm. Involucres hemispheric, 1.4–2 × 1–2 cm, phyllary margins thinly tomentose or glabrate. Phyllaries 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. Corollas 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. Cypselae gray or brown, 3.7–4.5 mm, apical collars not differentiated; pappi 10–15 mm. 2n = 34.
Life form perennial
Growth form herb
Growth support free-standing
Foliage retention deciduous
Sexuality hermaphrodite
Pollination -
Spread -
Mature width (meter) -
Mature height (meter) 1.0 - 3.0
Root system creeping-root tap-root
Rooting depth (meter) -
Root diameter (meter) -
Flower color
Blooming months
JanFebMar
AprMayJun
JulAugSep
OctNovDec
Fruit color -
Fruiting months -
Nitrogen fixer -
Photosynthetic pathway -

Environment

Light 7-9
Soil humidity 5-7
Soil texture 3-4
Soil acidity -
Soil nutriment -
Hardiness (USDA) -

Usage

Uses -
Edible -
Therapeutic use -
Human toxicity -
Animal toxicity -

Cultivation

Mode -
Germination duration (days) 15 - 18
Germination temperacture (C°) 21 - 23
Germination luminosity -
Germination treatment -
Minimum temperature (C°) -
Optimum temperature (C°) -
Size -
Vigor -
Productivity -

Distribution

Cirsium rydbergii world distribution map, present in United States of America

Identifiers

LSID urn:lsid:ipni.org:names:59151-2
WFO ID wfo-0000044946
COL ID VJD5
BDTFX ID -
INPN ID -
Wikipedia (EN) Link
Wikipedia (FR)

Synonyms

Cirsium lactucinum Cirsium rydbergii