Flora of North America species comparison

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Eriogonum brevicaule

Eriogonum effusum

shortstem buckwheat, shortstem wild buckwheat

spreading buckwheat, spreading wild buckwheat
Habit Herbs, matted, cespitose, pulvinate, erect or spreading, sometimes scapose, (0.3–)1–5 × 1–5(–8) dm, tomentose to floccose or glabrous, grayish or greenish to green. 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.
Stems

matted to spreading, occasionally with persistent leaf bases, up to 1/4 or more height of plant;

caudex stems matted or spreading;

aerial flowering stems spreading to erect or nearly so, slender, rarely stout, solid, not fistulose, (0.4–)0.5–2(–2.5) dm, glabrous, floccose, or sparsely to densely tomentose to lanate.

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.
Leaves

basal or more commonly sheathing 1–7(–15) cm up stem, 1 per node;

petiole 0.2–2(–4) cm, tomentose to floccose;

blade linear, oblanceolate, or spatulate to elliptic, (0.2–)1–10(–12) × 0.1–0.9(–1.2) cm, densely tomentose abaxially, less so to floccoseadaxially, margins plane or revolute, sometimes crenulate.

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.
Inflorescences

cymose, subumbellate, umbellate, or capitate, (1–)3–10(–25) × (0.7–)1–10(–15) cm;

branches dichotomous, sometimes absent, tomentose to floccose or glabrous;

bracts 3, triangular, scalelike, 1–3(–5) mm.

cymose, 10–30(–40) × 10–40 cm;

branches dichotomous, white-floccose to glabrate or subglabrous;

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

absent or erect, 0.3–3 cm, tomentose to floccose or glabrous.

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

1 per node or 3–7(–9) per cluster, turbinate to turbinate-campanulate, 1.5–4(–5) × (1–)1.5–3(–3.5) mm, tomentose to floccose or glabrous;

teeth 5, erect to spreading, 0.3–1 mm.

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

teeth 5, erect, 0.3–0.6 mm.
Flowers

(1–)2–4 mm;

perianth various shades of white to cream or yellow, glabrous or pubescent;

tepals connate proximal 1/4–1/3, monomorphic, lanceolate, oblong to obovate or ovate to oval;

stamens exserted, 2–4 mm;

filaments pilose basally.

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.
Achenes

light brown to brown, 2–3 mm, glabrous except for roughened to papillate beak.

brown, 2–2.5 mm, glabrous.

Eriogonum brevicaule

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

Varieties 8 (8 in the flora).

Eriogonum brevicaule is highly variable, and the variation has yet to be fully resolved taxonomically. The expressions recognized here will encompass the vast majority of populations. The extreme variation previously under the name var. laxifolium is now reduced with the recognition of var. bannockense (low-elevation or northern phase), var. nanum, and var. caelitum (high-elevation, southern phases).

Essentially all of the following species (28–63 below) belong to the Eriogonum brevicaule complex. Eriogonum desertorum, E. loganum, E. spathulatum, E. ostlundii, and E. artificis are allied to the complex associated with var. laxifolium, while E. natum is related to var. cottamii. Eriogonum viridulum and E. ephedroides are allied to E. brevicaule var. brevicaule as are E. contortum and E. acaule. Eriogonum brandegeei is also related, but exactly how is less certain. Allied to this complex of species are on the one hand those related to E. batemanii, and on the other all of the matted perennials belonging to the E. ochrocephalum complex. Essentially all of these species form relatively small populations on discrete edaphic sites and are well isolated one from the other. Unfortunately, a clear separation of E. brevicaule from E. desertorum, E. loganum, and E. spathulatum is not always possible.

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

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.)
Key
1. Flowering stems and inflorescence branches glabrous
→ 2
1. Flowering stems and inflorescence branches floccose to tomentose or lanate
→ 3
2. Plants not pulvinate or cespitose, (0.8-)1.5-5 dm; inflorescences cymose, open, divided 3 times or more; widespread
var. brevicaule
2. Plants pulvinate and cespitose, 0.3-1.5(-1.8) dm; inflorescences capitate or umbellate to cymose and divided 1-2 times; Utah
var. nanum
3. Perianths pubescent; se Montana, ne Wyoming
var. canum
3. Perianths glabrous; sc Idaho, ne Nevada, Utah, sw Wyoming, not se Montana or ne Wyoming
→ 4
4. Inflorescences divided (2-)3-5 times; perianths usually yellow, rarely ochroleucous
→ 5
4. Inflorescences capitate or umbellate to cymose and divided 1-2 times; perianths ochroleucous or yellow
→ 6
5. Flowers (1-)1.5-2.5 mm; sw Wyoming
var. micranthum
5. Flowers (2.5-)3-4 mm; Utah
var. cottamii
6. Leaf blades linear to narrowly oblanceolate; inflorescences capitate or divided
→ 7
6. Leaf blades linear, oblanceolate, or narrowly oblanceolate to elliptic; inflorescences capitate. [8. Shifted to left margin.—Ed.]
→ 8
7. Leaf blades (1.5-)3-9(-12) × 0.1-0.5(-0.7) cm, tomentose abaxially, less so and grayish or occasionally greenish adaxially, margins usually revolute, occasionally plane; perianths ochroleucous or yellow; n Utah, se Idaho, below 2800 m
var. laxifolium
7. Leaf blades 0.2-4.5(-5) × (0.2-)0.3-0.6(-0.7) cm, tomentose abaxially, thinly floccose and bright green adaxially, margins plane or slightly thickened; perianths yellow; c Utah, above 2700 m
var. caelitum
8. Leaf blades and flowering stems bright green under the thinly floccose pubescence; ne Nevada and nw Utah
var. laxifolium
8. Leaf blades and flowering stems usually grayish to dull greenish under tomentum, rarely thinly floccose; se Idaho and sw Wyoming s to n Utah and ne Nevada
→ 9
9. Leaf margins crenulate; leaf blades narrowly oblanceolate to narrowly elliptic, (0.3-)0.5-1.5(-2) × 0.2-0.5(-7) cm, densely white-tomentose abaxially, floccose and greenish adaxially
var. nanum
9. Leaf margins usually plane (rarely crenulate in Wyoming); leaf blades narrowly oblanceolate to oblanceolate, (0.8-)1-4(-4.5) × (0.3-)0.4-0.8 cm, densely tomentose abaxially, tomentose to floccose and grayish to greenish adaxially
var. bannockense
Source FNA vol. 5, p. 264. FNA vol. 5, p. 248.
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. 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. 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
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
Subordinate taxa
E. brevicaule var. bannockense, E. brevicaule var. brevicaule, E. brevicaule var. caelitum, E. brevicaule var. canum, E. brevicaule var. cottamii, E. brevicaule var. laxifolium, E. brevicaule var. micranthum, E. brevicaule var. nanum
Synonyms E. campanulatum subsp. brevicaule E. microthecum var. effusum
Name authority Nuttall: Proc. Acad. Nat. Sci. Philadelphia 4: 15. (1848) Nuttall: Proc. Acad. Nat. Sci. Philadelphia 4: 15. (1848)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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