Eriogonum corymbosum var. orbiculatum

(S. Stokes) Reveal & Brotherson

Great Basin Naturalist 27: 221. 1968.

Common names: Orbicular-leaf wild buckwheat
Endemic
Basionym: Eriogonum effusum subsp. orbiculatum S. Stokes Eriogonum, 79. 1936
Treatment appears in FNA Volume 5. Treatment on page 258. Mentioned on page 256.

Shrubs, (3–) 5–15 × 5–15 dm. Leaves cauline 1/2 or more length of flowering-stem; petiole 0.5–1.5 cm; blade broadly ovate to nearly orbiculate, 1–3 (–3.5) × 1–3 (–3.5) cm, floccose to tomentose on both surfaces or floccose adaxially. Inflorescences compact and rather flat-topped, 3–10 cm; branches densely tomentose. Involucres 2–3.5 × 1.5–2.5 mm. Flowers 2.5–3 mm; perianth white, glabrous.


Phenology: Flowering Aug–Oct.
Habitat: Sandy to gravelly flats, washes, slopes, mixed grassland, saltbush, blackbrush, and sagebrush communities, pinyon-juniper woodlands
Elevation: 900-1600(-2300) m

Discussion

Variety orbiculatum is encountered in northeastern Arizona (Coconino and Navajo counties), western Colorado (Mesa, Montezuma, San Juan, and San Miguel counties), and southeastern Utah (Emery, Garfield, Grand, Kane, San Juan, and Wayne counties). It is worthy of the serious horticultural efforts now being made to develop cultivars for the arid garden, with selection development emphasizing large, round, fully flowering shrubs capable of surviving a wide range of temperatures. A mature plant in full flower is a remarkable sight. The hemispheric shrubs wholly and densely blanketed by bright white flowers and set against the deep red sands and sandy-clay hills in Monument Valley are seen in numerous photographs and several John Ford movies. An expression from Gypsum Valley, San Miguel County, Colorado, may well reprecent an undescribed variety allied to var. orbiculatum.

Selected References

None.

Lower Taxa

None.

"/2" 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."dm" is not declared as a valid unit of measurement for this property.

0.25 cm2.5 mm <br />0.0025 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
included +  and exserted +
3-gonous +
usually red +  and cream or yellow +
oblong +  and ellipsoid or oval +
acute;obtuse or rounded +
James L. Reveal +
(S. Stokes) Reveal & Brotherson +
deciduous +  and persistent +
stipelike +
Eriogonum effusum subsp. orbiculatum +
occasional +
papillate +
awn-tipped +  and simple +
3 cm30 mm <br />0.03 m <br /> (3.5 cm35 mm <br />0.035 m <br />) +
3 cm30 mm <br />0.03 m <br /> (3.5 cm35 mm <br />0.035 m <br />) +
tannish +  and white +
1 cm10 mm <br />0.01 m <br /> (3 cm30 mm <br />0.03 m <br />) +
floccose +  and tomentose +
broadly ovate;nearly orbiculate +
1 cm10 mm <br />0.01 m <br /> (3 cm30 mm <br />0.03 m <br />) +
not awn-tipped +
0.3 cm3 mm <br />0.003 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
glandular +, pubescent +  and glabrous +
triangular +  and scale-like +
1 cm10 mm <br />0.01 m <br /> (2.5 cm25 mm <br />0.025 m <br />) +
not brittle +
spreading +  and erect +
scabrellous +
ridged +, angled +  and round +
spreading +  and erect +
whorled +, opposite +  and alternate +
Orbicular-leaf wild buckwheat +
Ariz. +, Colo. +  and Utah. +
900-1600(-2300) m +
0.15 cm1.5 mm <br />0.0015 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
unisexual +, , +  and bisexual +
not attenuate +
0.25 cm2.5 mm <br />0.0025 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
decumbent to erect +  and prostrate +
not fistulose +
stout;slender +
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 to gravelly flats, washes, slopes, mixed grassland, saltbush, blackbrush, and sagebrush communities, pinyon-juniper woodlands +
reduced +
open +, umbellate +, capitate +  and cymose +
capitate +  and subcapitate +
1 cm10 mm <br />0.01 m <br /> (3 cm30 mm <br />0.03 m <br />) +
25 cm250 mm <br />0.25 m <br /> (30 cm300 mm <br />0.3 m <br />) +
3 cm30 mm <br />0.03 m <br /> (20 cm200 mm <br />0.2 m <br />) +
3 cm30 mm <br />0.03 m <br /> (10 cm100 mm <br />0.1 m <br />) +
2 cm20 mm <br />0.02 m <br /> (25 cm250 mm <br />0.25 m <br />) +
connate +  and free +
0.1 cm1 mm <br />0.001 m <br /> (0.15 cm1.5 mm <br />0.0015 m <br />) +
0.2 cm2 mm <br />0.002 m <br /> (0.25 cm2.5 mm <br />0.0025 m <br />) +
0.2 cm2 mm <br />0.002 m <br /> (0.35 cm3.5 mm <br />0.0035 m <br />) +
nonmembranous +
0.15 cm1.5 mm <br />0.0015 m <br /> (0.25 cm2.5 mm <br />0.0025 m <br />) +
in whorls +, opposite +, alternate +  and rosulate +
persistent +
bractlike +
crenulate +
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 /> (1.5 cm15 mm <br />0.015 m <br />) +
Flowering Aug–Oct. +
homostylous +  and 3-carpellate +
Great Basin Naturalist +
, +  and solid +
slender;stout +
persistent +
0.4 cm4 mm <br />0.004 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
included +  and slightly exserted +
0.1 cm1 mm <br />0.001 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +
decumbent to erect +  and prostrate +
erect +  and spreading +
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 effusum subsp. corymbosum +
chambered +  and solid +
slender +  and stout +
Eriogonum corymbosum var. orbiculatum +
Eriogonum corymbosum +
variety +
emarginate +  and entire +
0 +  and 1/2 +
1/4 +  and 1/3 +
oblanceolate +  and spatulate +
coriaceous +
0.03 cm0.3 mm <br />3.0e-4 m <br /> (0.1 cm1 mm <br />0.001 m <br />) +
persistent +
membranous +
pubescent +  and glabrous +
greenish +  and grayish +
erect;spreading;erect;spreading +
reddish-brown-tomentose +  and floccose or glabrous +
synoecious +, monocarpic +, polycarpic +  and , +
3 +, 2 +  and 1 +