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spreading buckwheat, spreading wild buckwheat

bull mountain buckwheat, Cronquist's wild buckwheat

Habit Shrubs, spreading, not scapose, (1.5–)2–5(–7) × 5–15 dm, grayish- to reddish-brown-tomentose to floccose and gray or, rarely, thinly floccose and greenish. Herbs, spreading, not scapose, (0.7–)1–1.5(–4) × 3–8 dm, glabrous, grayish.
Stems

spreading to erect, typically without persistent leaf bases, up to 1/2 height of plant;

caudex stems absent;

aerial flowering stems erect to spreading, slender, solid, not fistulose, 0.3–0.8 dm, floccose or glabrous.

spreading, usually with persistent leaf bases, up to 1/4 height of plant;

caudex stems spreading;

aerial flowering stems spreading to erect, slender, solid, not fistulose, 0.5–1 dm, glabrous, tomentose among leaves.

Leaves

cauline, 1 per node;

petiole 0.2–0.7 cm, tomentose to floccose;

blade oblanceolate to oblong or obovate, (1–)1.5–3 × (0.2–)0.3–0.7 cm, densely white-tomentose abaxially, white-floccose to glabrate or green and glabrous adaxially, margins plane.

sheathing up stems 1–4 cm, 1 per node;

petiole 0.3–0.8 cm, tomentose;

blade elliptic, 0.5–2 × 0.4–1 cm, densely white-tomentose abaxially, sparsely so and greenish adaxially, margins crenulate.

Inflorescences

cymose, 10–30(–40) × 10–40 cm;

branches dichotomous, white-floccose to glabrate or subglabrous;

bracts 3, scalelike, triangular, 0.5–2(–5) mm.

subcapitate to cymose, 1–7 × 1–5 cm;

branches dichotomous, glabrous;

bracts 3, scalelike, triangular, 1 mm.

Peduncles

absent or mostly erect, slender, 0.3–2.5 cm, floccose.

absent.

Involucres

1 per node, turbinate, 1.5–2.5(–3) × 1–2 mm, tomentose to floccose;

teeth 5, erect, 0.3–0.6 mm.

1 per node or 2–4 per cluster, turbinate, (2.5–)3–3.5 × 2–2.5 mm, glabrous;

teeth 5, erect, 0.6–1 mm.

Flowers

2–4 mm;

perianth yellow, glabrous;

tepals connate proximal 1/4, essentially monomorphic, elliptic to obovate;

stamens mostly exserted, 2–4.5 mm;

filaments sparsely pilose proximally.

(1.5–)2–3 mm;

perianth white, glabrous;

tepals connate proximal 1/3, monomorphic, oblanceolate;

stamens exserted, 2.5–4 mm;

filaments pilose proximally.

Achenes

brown, 2–2.5 mm, glabrous.

light brown, 2–2.5 mm, glabrous.

2n

= 40.

Eriogonum effusum

Eriogonum cronquistii

Phenology Flowering Jun–Sep. Flowering Jul–Sep.
Habitat Sandy to rocky slopes and flats, mixed grassland and sagebrush communities, juniper and montane conifer woodlands Granitic talus slopes and outcrops, sagebrush communities, pinyon-juniper woodlands
Elevation 1200-2500 m (3900-8200 ft) 2500-2800 m (8200-9200 ft)
Distribution
from FNA
CO; MT; NE; NM; SD; WY
[WildflowerSearch map]
[BONAP county map]
from FNA
UT
[BONAP county map]
Discussion

Eriogonum effusum is rather common on the northern Great Plains and along the eastern slope of the Rocky Mountains in central and eastern Colorado, southeastern Montana, western Nebraska, northern New Mexico, southwestern South Dakota, and southeastern Wyoming. Some specimens from Chaffee County, Colorado, are thinly floccose and greenish (Atwood & Welsh 29689, BRY) and thus similar to E. leptocladon. A collection from Pyramid Lake, Washoe County, Nevada (Frandsen & Brown 182, NESH) is clearly mislabeled. A roadside collection of E. effusum gathered near Little America, Sweetwater County, Wyoming, in 1961 (G. Mason 4025, ASU) was an introduction that has not persisted.

The spreading wild buckwheat is occasionally merged with Eriogonum microthecum even though the two are morphologically distinct and their ranges do not overlap. Plants in New Mexico are sometimes difficult to distinguish from the related E. leptocladon var. ramosissimum. The species is the food plant for the Rita dotted-blue butterfly (Euphilotes rita). A hybrid between Eriogonum effusum and E. pauciflorum has been named E. ×nebraskense Rydberg [E. multiceps Nees subsp. nebraskense (Rydberg) S. Stokes; E. pauciflorum Pursh var. nebraskense (Rydberg) Reveal]. The hybrid is known from Weld County, Colorado; Cheyenne and Kimball counties, Nebraska; and Converse and Platte counties, Wyoming.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Of conservation concern.

Eriogonum cronquistii is known only from the western slope and summit of Bull Mountain, Henry Mountains, Garfield County. The Bureau of Land Management considers it a “sensitive” species.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 5, p. 248. FNA vol. 5, p. 273.
Parent taxa Polygonaceae > subfam. Eriogonoideae > Eriogonum > subg. Eucycla Polygonaceae > subfam. Eriogonoideae > Eriogonum > subg. Eucycla
Sibling taxa
E. abertianum, E. acaule, E. alatum, E. aliquantum, E. allenii, E. alpinum, E. ammophilum, E. ampullaceum, E. androsaceum, E. anemophilum, E. angulosum, E. annuum, E. apiculatum, E. apricum, E. arborescens, E. arcuatum, E. aretioides, E. argillosum, E. argophyllum, E. arizonicum, E. artificis, E. atrorubens, E. baileyi, E. batemanii, E. bicolor, E. bifurcatum, E. brachyanthum, E. brachypodum, E. brandegeei, E. breedlovei, E. brevicaule, E. butterworthianum, E. caespitosum, E. capillare, E. cernuum, E. chrysops, E. cinereum, E. cithariforme, E. clavatum, E. clavellatum, E. codium, E. collinum, E. coloradense, E. compositum, E. concinnum, E. congdonii, E. contiguum, E. contortum, E. correllii, E. corymbosum, E. covilleanum, E. crocatum, E. cronquistii, E. crosbyae, E. cusickii, E. darrovii, E. dasyanthemum, E. davidsonii, E. deflexum, E. deserticola, E. desertorum, E. diatomaceum, E. diclinum, E. divaricatum, E. douglasii, E. eastwoodianum, E. elatum, E. elegans, E. elongatum, E. ephedroides, E. eremicola, E. eremicum, E. ericifolium, E. esmeraldense, E. evanidum, E. exaltatum, E. exilifolium, E. fasciculatum, E. flavum, E. fusiforme, E. giganteum, E. gilmanii, E. glandulosum, E. gordonii, E. gossypinum, E. gracile, E. gracilipes, E. gracillimum, E. grande, E. greggii, E. gypsophilum, E. havardii, E. heermannii, E. helichrysoides, E. hemipterum, E. heracleoides, E. hieracifolium, E. hirtellum, E. hirtiflorum, E. hoffmannii, E. holmgrenii, E. hookeri, E. howellianum, E. hylophilum, E. incanum, E. inerme, E. inflatum, E. intrafractum, E. jamesii, E. jonesii, E. kelloggii, E. kennedyi, E. kingii, E. lachnogynum, E. lancifolium, E. latens, E. latifolium, E. lemmonii, E. leptocladon, E. leptophyllum, E. libertini, E. lobbii, E. loganum, E. lonchophyllum, E. longifolium, E. luteolum, E. maculatum, E. mancum, E. marifolium, E. mensicola, E. microthecum, E. mitophyllum, E. mohavense, E. molestum, E. mortonianum, E. multiflorum, E. natum, E. nealleyi, E. nervulosum, E. nidularium, E. niveum, E. nortonii, E. novonudum, E. nudum, E. nummulare, E. nutans, E. ochrocephalum, E. ordii, E. ostlundii, E. ovalifolium, E. palmerianum, E. panamintense, E. panguicense, E. parishii, E. parvifolium, E. pauciflorum, E. pelinophilum, E. pendulum, E. pharnaceoides, E. plumatella, E. polycladon, E. polypodum, E. prattenianum, E. prociduum, E. pulchrum, E. pusillum, E. pyrolifolium, E. racemosum, E. reniforme, E. ripleyi, E. rixfordii, E. robustum, E. rosense, E. roseum, E. rotundifolium, E. rubricaule, E. rupinum, E. salicornioides, E. saxatile, E. scabrellum, E. scopulorum, E. shockleyi, E. siskiyouense, E. smithii, E. soliceps, E. soredium, E. spathulatum, E. spectabile, E. spergulinum, E. sphaerocephalum, E. strictum, E. subreniforme, E. suffruticosum, E. temblorense, E. tenellum, E. ternatum, E. terrenatum, E. thomasii, E. thompsoniae, E. thornei, E. thurberi, E. thymoides, E. tiehmii, E. tomentosum, E. trichopes, E. tripodum, E. truncatum, E. tumulosum, E. twisselmannii, E. umbellatum, E. ursinum, E. vestitum, E. villiflorum, E. vimineum, E. viridescens, E. viridulum, E. viscidulum, E. visheri, E. watsonii, E. wetherillii, E. wootonii, E. wrightii, E. zionis
E. abertianum, E. acaule, E. alatum, E. aliquantum, E. allenii, E. alpinum, E. ammophilum, E. ampullaceum, E. androsaceum, E. anemophilum, E. angulosum, E. annuum, E. apiculatum, E. apricum, E. arborescens, E. arcuatum, E. aretioides, E. argillosum, E. argophyllum, E. arizonicum, E. artificis, E. atrorubens, E. baileyi, E. batemanii, E. bicolor, E. bifurcatum, E. brachyanthum, E. brachypodum, E. brandegeei, E. breedlovei, E. brevicaule, E. butterworthianum, E. caespitosum, E. capillare, E. cernuum, E. chrysops, E. cinereum, E. cithariforme, E. clavatum, E. clavellatum, E. codium, E. collinum, E. coloradense, E. compositum, E. concinnum, E. congdonii, E. contiguum, E. contortum, E. correllii, E. corymbosum, E. covilleanum, E. crocatum, E. crosbyae, E. cusickii, E. darrovii, E. dasyanthemum, E. davidsonii, E. deflexum, E. deserticola, E. desertorum, E. diatomaceum, E. diclinum, E. divaricatum, E. douglasii, E. eastwoodianum, E. effusum, E. elatum, E. elegans, E. elongatum, E. ephedroides, E. eremicola, E. eremicum, E. ericifolium, E. esmeraldense, E. evanidum, E. exaltatum, E. exilifolium, E. fasciculatum, E. flavum, E. fusiforme, E. giganteum, E. gilmanii, E. glandulosum, E. gordonii, E. gossypinum, E. gracile, E. gracilipes, E. gracillimum, E. grande, E. greggii, E. gypsophilum, E. havardii, E. heermannii, E. helichrysoides, E. hemipterum, E. heracleoides, E. hieracifolium, E. hirtellum, E. hirtiflorum, E. hoffmannii, E. holmgrenii, E. hookeri, E. howellianum, E. hylophilum, E. incanum, E. inerme, E. inflatum, E. intrafractum, E. jamesii, E. jonesii, E. kelloggii, E. kennedyi, E. kingii, E. lachnogynum, E. lancifolium, E. latens, E. latifolium, E. lemmonii, E. leptocladon, E. leptophyllum, E. libertini, E. lobbii, E. loganum, E. lonchophyllum, E. longifolium, E. luteolum, E. maculatum, E. mancum, E. marifolium, E. mensicola, E. microthecum, E. mitophyllum, E. mohavense, E. molestum, E. mortonianum, E. multiflorum, E. natum, E. nealleyi, E. nervulosum, E. nidularium, E. niveum, E. nortonii, E. novonudum, E. nudum, E. nummulare, E. nutans, E. ochrocephalum, E. ordii, E. ostlundii, E. ovalifolium, E. palmerianum, E. panamintense, E. panguicense, E. parishii, E. parvifolium, E. pauciflorum, E. pelinophilum, E. pendulum, E. pharnaceoides, E. plumatella, E. polycladon, E. polypodum, E. prattenianum, E. prociduum, E. pulchrum, E. pusillum, E. pyrolifolium, E. racemosum, E. reniforme, E. ripleyi, E. rixfordii, E. robustum, E. rosense, E. roseum, E. rotundifolium, E. rubricaule, E. rupinum, E. salicornioides, E. saxatile, E. scabrellum, E. scopulorum, E. shockleyi, E. siskiyouense, E. smithii, E. soliceps, E. soredium, E. spathulatum, E. spectabile, E. spergulinum, E. sphaerocephalum, E. strictum, E. subreniforme, E. suffruticosum, E. temblorense, E. tenellum, E. ternatum, E. terrenatum, E. thomasii, E. thompsoniae, E. thornei, E. thurberi, E. thymoides, E. tiehmii, E. tomentosum, E. trichopes, E. tripodum, E. truncatum, E. tumulosum, E. twisselmannii, E. umbellatum, E. ursinum, E. vestitum, E. villiflorum, E. vimineum, E. viridescens, E. viridulum, E. viscidulum, E. visheri, E. watsonii, E. wetherillii, E. wootonii, E. wrightii, E. zionis
Synonyms E. microthecum var. effusum E. corymbosum var. cronquistii
Name authority Nuttall: Proc. Acad. Nat. Sci. Philadelphia 4: 15. (1848) Reveal: Madroño 19: 289, fig. 1. (1969)
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