Cirsium scariosum var. citrinum

(Petrak) D. J. Keil

Sida 21: 215. 2004.

Common names: La Graciosa thistle
Conservation concern
Basionym: Cirsium quercetorum var. citrinum Petrak Beih. Bot. Centralbl. 35(2): 363. 1917
Synonyms: Carduus validus Greene Cirsium drummondii subsp. latisquamum Petrak Cirsium loncholepis Petrak
Treatment appears in FNA Volume 19. Treatment on page 158. Mentioned on page 155, 159, 161.

Plants acaulescent to bushy and mounding or erect, 5–100 cm. Stems usually 1, branched distally or openly so throughout, leafy, glabrous or thinly arachnoid-tomentose. Leaves: blades oblanceolate to elliptic, deeply pinnately lobed, longer spines slender to stout, usually 1 cm or shorter, abaxial faces usually green, glabrous or glabrate or thinly to densely tomentose, adaxial faces glabrous to sparingly villous with septate trichomes or thinly arachnoid-tomentose. Heads 2–many, subsessile or short-pedunculate, in ± congested corymbiform to subcapitate arrays at stem tips (in age clustered axillary heads often developing), subtended and ± overtopped by distal leaves or these ± reduced. Involucres 2.5–4 cm. Phyllaries: outer and mid lanceolate to ovate, spines 1–6 mm, slender and weak or broad and flat; apices of inner stiffly erect or thin and often contorted, acuminate and entire or rarely toothed. Corollas white or lightly purple-tinged (purple), (21–) 26–35 mm, tubes (11–) 14–22 mm, throats 6–9 mm, lobes (4–) 5.5–8 mm; style tips 4–6 mm. Cypselae 4.5–5 mm; pappi 23–31 mm. 2n = 34 (as Cirsium loncholepis).


Phenology: Flowering mostly spring–summer (Apr–Jul, occasionally as late as Nov in coastal sites).
Habitat: Wet ground, meadows, pastures, springs, marshes, both coastal and interior
Elevation: 0–2500 m

Distribution

V19-157-distribution-map.gif

Calif., Mexico (Baja California?)

Discussion

Of conservation concern.

Variety citrinum is the southern California race of Cirsium scariosum. As is the case in other varieties of this complex, taxonomic recognition has been given to local populations, named on the basis of limited samples. After examining specimens gathered from various populations in southern California, I realized that although exemplars of local populations may have distinctive features, there are so many intermediates that recognizing any of the local races becomes arbitrary. Individuals treated as Cirsium loncholepis (from coastal sites bordering the mouth of the Santa Maria River and adjacent regions in San Luis Obispo and Santa Barbara counties) are often indistinguishable from plants of upland populations of the San Emigdio Mountains (Kern and Ventura counties) in the vicinity of the headwaters of the Cuyama River, a tributary of the Santa Maria River. Other individuals from the San Emigdio Mountains cannot be distinguished from plants of other upland and lowland southern California sites ranging south to San Diego County.

Cirsium loncholepis was recognized by the California Department of Fish and Game in 1990 as a threatened species, and in 2000 by the U.S. Fish and Wildlife Service as endangered. Its conservation status is being reevaluated in light of my conclusions about its taxonomy. I believe that the combined taxon, C. scariosum var. citrinum, should still be of conservation concern. Many of the collections from southern California are from highly developed areas, and the number and size of extant populations need to be evaluated.

Interspecific hybridization involving var. citrinum is known or suspected in several instances. A putative hybrid between it and Cirsium occidentale var. occidentale from dunes in San Luis Obispo County combines the leaf pubescence and arachnoid involucre of C. occidentale with features of C. scariosum. An apparent hybrid between var. citrinum and the strikingly different C. rhothophilum was collected from coastal dunes in northern Santa Barbara County. A population of unusual, purple-flowered individuals from Price Canyon northeast of Los Alamos in Santa Barbara County may be the product of past hybridization with another species. These plants are tall (1–1.6 m according to label data) and their stems and distal leaf faces are villous with septate trichomes.

Selected References

None.

Lower Taxa

None.

"fine" is not a number."narrower" is not a number."broad" is not a number.

glabrate or +  and thinly densely tomentose +
arachnoid-tomentose +, glabrous +  and sparingly villous +
short-tailed +
spineless +  and twisted +
dentate +, entire +  and spine-tipped +
innermost +
scarious +
corymbiform to subcapitate +
indeterminate +  and determinate +
David J. Keil +
(Petrak) D. J. Keil +
winged-petiolate +  and sessile +
decurrent +
Cirsium quercetorum var. citrinum +
compound +  and simple +
linear to elliptic +
5 cm50 mm <br />0.05 m <br /> (20 cm200 mm <br />0.2 m <br />) +
lobed;oblanceolate;elliptic +
3cm;7cm +
10-nerved or 20-nerved +  and rugose +
tawny +  and white +
? (?) +  and ? (?) +
La Graciosa thistle +
actinomorphic +
2.1 cm21 mm <br />0.021 m <br /> (2.6 cm26 mm <br />0.026 m <br />) +
purple-tinged +  and white +
2.6 cm26 mm <br />0.026 m <br /> (3.5 cm35 mm <br />0.035 m <br />) +
light +  and dark-brown +
compressed +  and ovoid +
fertile +  and bisexual +
Calif. +  and Mexico (Baja California?) +
0–2500 m +
gray-canescent +  and glabrous +
pistillate +, staminate +  and neuter +
winged +  and beaked +
dispersed +
Wet ground, meadows, pastures, springs, marshes, both coastal and interior +
short-pedunculate +  and subsessile +
crowded +  and singly +
indeterminate +
each +  and sessile +
2 cm20 mm <br />0.02 m <br /> (4 cm40 mm <br />0.04 m <br />) +
glabrate +  and arachnoid +
ovoid;hemispheric +
2.5 cm25 mm <br />0.025 m <br /> (4 cm40 mm <br />0.04 m <br />) +
1.5 cm15 mm <br />0.015 m <br /> (6 cm60 mm <br />0.06 m <br />) +
sessile +  and petiolate +
cauline +  and basal +
bristle-tipped +
0.4 cm4 mm <br />0.004 m <br /> (0.55 cm5.5 mm <br />0.0055 m <br />) +
lobed +, spinose-dentate +, linear-lanceolate +  and broadly triangular +
slender +  and stout +
1 cm10 mm <br />0.01 m <br /> (?) +
0.2 cm2 mm <br />0.002 m <br /> (1.5 cm15 mm <br />0.015 m <br />) +
entire +  and dentate +
scarious-fringed +  and entire +
rounded +
2-carpellate +
white +  and tan +
persistent +
2.3 cm23 mm <br />0.023 m <br /> (3.1 cm31 mm <br />0.031 m <br />) +
0 cm0 mm <br />0 m <br /> (10 cm100 mm <br />0.1 m <br />) +
Flowering mostly spring–summer (Apr–Jul, occasionally as late as Nov in coastal sites). +
middle +  and outer +
weakly to strongly +
short-caulescent +  and acaulescent +
papillate +  and smooth +
bearing subulate enations +, hairy +  and bristly +
flat;convex +
glutinous +
tawny;white +
setiform +  and plumose +
exalbuminous +
subequal +
Conservation concern +
erect +  and spreading +
flattened +
0.1 cm1 mm <br />0.001 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
leafy +  and branched +
appendaged +  and truncate +
dilated +  and swollen +
enlarged +
0.4 cm4 mm <br />0.004 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
Carduus validus +, Cirsium drummondii subsp. latisquamum +  and Cirsium loncholepis +
Cirsium scariosum var. citrinum +
Cirsium scariosum +
variety +
cylindric +
expanded +
0.6 cm6 mm <br />0.006 m <br /> (0.9 cm9 mm <br />0.009 m <br />) +
tipped +  and spineless +
scabro-denticulate +  and narrowed +
expanded +
bristly-dentate to coarsely +
1.1 cm11 mm <br />0.011 m <br /> (1.4 cm14 mm <br />0.014 m <br />) +
slender +
1.4 cm14 mm <br />0.014 m <br /> (2.2 cm22 mm <br />0.022 m <br />) +
taprooted +, caulescent +  and acaulescent +
perennial +  and biennial +
0 cm0 mm <br />0 m <br /> (200 cm2,000 mm <br />2 m <br />) +
plant +, mounding +  and bushy +