Eriogonum arcuatum var. xanthum

(Small) Reveal

Harvard Pap. Bot. 9: 157. 2004.

Common names: Ivy League wild buckwheat
Endemic
Basionym: Eriogonum xanthum Small Bull. Torrey Bot. Club. 33: 51. 1906
Synonyms: Eriogonum chloranthum Greene Eriogonum flavum subsp. chloranthum (Greene) S. Stokes Eriogonum flavum var. xanthum (Small) S. Stokes Eriogonum jamesii var. xanthum (Small) Reveal
Treatment appears in FNA Volume 5. Treatment on page 370. Mentioned on page 369.

Plants compact mats, 3–10 dm wide. Aerial flowering-stems 0.2–0.8 dm. Leaf-blades oblanceolate to oblong, 1–2.5 × 0.5–1 cm. Inflorescences capitate, often reduced to single involucre; bracts 0.3–1 × 0.2–0.7 cm. Involucres 4–6 × 3–5 mm. Flowers 6–7 mm.


Phenology: Flowering Jul–Sep.
Habitat: Sandy, gravelly to rocky or talus slopes, high-elevation grassland, sagebrush, and tundra communities, alpine conifer woodlands
Elevation: (2600-)3000-4000(-4200) m

Discussion

Variety xanthum is the subalpine to alpine expression of the species and is distributed along the backbone of the Colorado Rocky Mountains on many of the highest peaks (Chaffee, Clear Creek, Custer, El Paso, Fremont, Grand, Hinsdale, Huerfano, Lake, Larimer, Park, Saguache, Summit, and Teller counties). The plants are rather exquisite in the field and do well in cultivation.

Selected References

None.

Lower Taxa

None.

"dm" is not declared as a valid unit of measurement for this property."dm" is not declared as a valid unit of measurement for this property."dm" is not declared as a valid unit of measurement for this property."dm" is not declared as a valid unit of measurement for this property.

light-brown;brown +
included +  and exserted +
3-gonous +
usually red +  and cream or yellow +
oblong +  and ellipsoid or oval +
James L. Reveal +
(Small) Reveal +
deciduous +  and persistent +
stipelike +
0.07 cm0.7 mm <br />7.0e-4 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
Eriogonum xanthum +
awn-tipped +  and simple +
greenish +  and grayish +
0.5 cm5 mm <br />0.005 m <br /> (3 cm30 mm <br />0.03 m <br />) +
floccose +  and tomentose +
oblong;elliptic +
0.5 cm5 mm <br />0.005 m <br /> (1.5 cm15 mm <br />0.015 m <br />) +
not awn-tipped +
0.3 cm3 mm <br />0.003 m <br /> (1 cm10 mm <br />0.01 m <br />) +
glandular +, pubescent +  and glabrous +
scale-like +
0.2 cm2 mm <br />0.002 m <br /> (0.7 cm7 mm <br />0.007 m <br />) +
grooved +, disarticulating +  and dichotomous +
not brittle +
scabrellous +
spreading +  and erect +
whorled +, opposite +  and alternate +
Ivy League wild buckwheat +
(2600-)3000-4000(-4200) m +
curved +  and straight +
unisexual +  and bisexual +
attenuate +
0.6 cm6 mm <br />0.006 m <br /> (0.7 cm7 mm <br />0.007 m <br />) +
decumbent to erect +  and prostrate +
not fistulose +
unwinged +  and winged +
black +, red +, brown +  and yellowish +
exserted +  and included +
pubescent +  and glabrous +
spheroidal +, 4-gonous +, lenticular +, biconvex +, discoid +, 3-gonous +  and 2-gonous +
Sandy, gravelly to rocky or talus slopes, high-elevation grassland, sagebrush, and tundra communities, alpine conifer woodlands +
compound-umbellate +  and umbellate +
cymelike +, paniclelike +, racemelike +  and spikelike +
connate +  and free +
0.4 cm4 mm <br />0.004 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
campanulate +
nonmembranous +
0.3 cm3 mm <br />0.003 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
1 cm10 mm <br />0.01 m <br /> (2.5 cm25 mm <br />0.025 m <br />) +
oblanceolate +  and oblong +
in whorls +, opposite +, alternate +  and rosulate +
persistent +
bractlike +
pubescent +  and glabrous +
not swollen +
orthotropous +
accrescent +
curved +  and straight +
erect to deflexed +
cylindric +  and urceolate +
accrescent +
fleshy +, indurate +  and membranous +
with extrafloral nectaries +  and not articulate +
tomentose +  and floccose +
0.5 cm5 mm <br />0.005 m <br /> (2 cm20 mm <br />0.02 m <br />) +
Flowering Jul–Sep. +
homostylous +  and 3-carpellate +
Harvard Pap. Bot. +
, +  and solid +
slender;stout +
persistent +
0.2 cm2 mm <br />0.002 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +
decumbent to erect +  and prostrate +
prostrate +  and erect +
glandular +, pubescent +  and glabrous +
penicillate +, fimbriate +  and capitate +
deciduous +  and persistent +
2-lobed +  and cylindric +
coriaceous +  and membranous +
consisting of a series +  and tubular +
distinct +
erect;spreading or recurved +
spreading;erect +
Eriogonum chloranthum +, Eriogonum flavum subsp. chloranthum +, Eriogonum flavum var. xanthum +  and Eriogonum jamesii var. xanthum +
chambered +  and solid +
slender +  and stout +
Eriogonum arcuatum var. xanthum +
Eriogonum arcuatum +
variety +
emarginate +  and entire +
1/4 +  and 1/3 +
lobed +  and laciniate +
coriaceous +
0.01 cm0.1 mm <br />1.0e-4 m <br /> (0.05 cm0.5 mm <br />5.0e-4 m <br />) +
persistent +
membranous +
pubescent +  and glabrous +
sericeous +, lanate +  and tomentose floccose or glabrous +
dioecious +, polygamodioecious +, synoecious +  and polycarpic +
annual +, biennial +  and perennial +
synoecious +, monocarpic +, polycarpic +  and , +
3 +, 2 +  and 1 +
0.15 cm1.5 mm <br />0.0015 m <br /> (0.7 cm7 mm <br />0.007 m <br />) +
0.2 cm2 mm <br />0.002 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +