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Thompson's buckwheat, Thompson's wild buckwheat

yellow turban

Habit Herbs, spreading, not scapose, 2–5(–6) × 2–5 dm, glabrous, green. Herbs, spreading, annual, 0.5–3 dm, glabrous, greenish, grayish, or reddish.
Stems

spreading, without persistent leaf bases, up to 1/5 height of plant;

caudex stems spreading, glabrous;

aerial flowering stems erect, slender, solid, not fistulose, 1.2–3 dm, glabrous, tomentose among leaves.

caudex absent;

aerial flowering stems erect, solid, not fistulose, 0.2–0.8 dm, glabrous except for few glands proximally.

Leaves

basal or sheathing up stem less than 2 cm, 1 per node;

petiole (0.1–)3–7(–10) cm, tomentose to floccose or glabrous;

blade linear or oblong to oblanceolate or elliptic, 2–8(–10) × 0.2–2.5(–3) cm, thinly to densely white-tomentose abaxially, glabrous and green adaxially, margins plane or slightly revolute.

basal;

petiole 1–3 cm;

blade oblong-ovate to round, 0.5–2.5(–3) × 0.4–2(–2.5) cm, densely white-tomentose abaxially, floccose to subglabrate and greenish adaxially, often with some glandular hairs, margins plane or rarely crenulate.

Inflorescences

cymose, open, 10–30 × 10–25 cm;

branches dichotomous, glabrous;

bracts 3, scalelike, linear, 2–5(–7) mm.

cymose, mostly open, 5–25 × 05–25 cm;

branches glabrous;

bracts 3, scalelike, 1–3 × 1–2 mm.

Peduncles

absent.

erect, mostly straight, slender, 0.1–5(–7) cm, glabrous.

Involucres

1 per node, turbinate, 2–3(–3.5) × 1–1.5(–2) mm, glabrous;

teeth 5, erect, 0.4–0.5 mm.

campanulate, 1–1.5(–1.7) × 1.5–3 mm, glandular-puberulent;

teeth 5, erect, 0.4–0.7 mm.

Flowers

3–3.5 mm;

perianth yellow or white, glabrous;

tepals connate only at base, monomorphic, oblong to obovate;

stamens slightly exserted, 3–3.5(–4) mm;

filaments sparsely pilose proximally.

1–1.7 mm in early anthesis, becoming 1.5–3 mm; yellow in early anthesis, becoming reddish yellow to red, glandular;

tepals dimorphic, those of outer whorl oblong-elliptic to obovate, those of inner whorl oblong;

stamens included, 1–1.5 mm;

filaments mostly glabrous.

Achenes

light brown to brown, 2.5–3 mm, glabrous except for slightly papillate beak.

dark brown, usually lenticular, 0.6–0.8 mm, glabrous.

2n

= 32.

Eriogonum thompsoniae

Eriogonum pusillum

Phenology Flowering Feb–Aug.
Habitat Sandy flats, washes, and slopes, saltbush, greasewood, creosote bush, and sagebrush communities, pinyon and/or juniper woodlands
Elevation 70-1300(-1600) m (200-4300(-5200) ft)
Distribution
from FNA
AZ; UT
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ; CA; NV; OR; UT
[WildflowerSearch map]
[BONAP county map]
Discussion

Varieties 3 (3 in the flora).

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

Eriogonum pusillum is common to abundant but rarely weedy. It is found mainly in the northern Mojave Desert and in the Great Basin of the Intermountain West of California and Nevada, extending just into southeastern Oregon, western Utah, and northwestern Arizona. It supposedly was found near Wickenburg in Maricopa County, California (M. E. Jones s.n., 5 May 1903, POM), well out of the known range of the species today. The San Benito River canyon site in San Benito County, California (Mason 5543; UC), also is notably disjunct, and although the species has not been recollected there, that location record is more reliable. The Plumas County record is based on an 1880 Austin collection (NY), and the location should be regarded as questionable.

Eriogonum pusillum is used as a food plant by the rare Mojave dotted-blue butterfly (Euphilotes mojave). Also, along with E. reniforme, it is an important food plant for juvenile desert tortoises (Gopherus agassizii). The Kawaiisu people of southern California gathered the achenes of E. pusillum, which were pounded into a powder and cooked into a mush or consumed dry (M. L. Zigmond 1981).

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

Key
1. Leaf blades linear, 3-8(-10) × 0.2-0.4(-0.6) cm
var. atwoodii
1. Leaf blades oblong to oblanceolate or elliptic; 2-5 × 0.8-2.5(-3) cm
→ 2
2. Perianths yellow
var. thompsoniae
2. Perianths white
var. albiflorum
Source FNA vol. 5, p. 261. FNA vol. 5, p. 404.
Parent taxa Polygonaceae > subfam. Eriogonoideae > Eriogonum > subg. Eucycla Polygonaceae > subfam. Eriogonoideae > Eriogonum > subg. Ganysma
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. 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. 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. 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. 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. thompsoniae var. albiflorum, E. thompsoniae var. atwoodii, E. thompsoniae var. thompsoniae
Synonyms E. corymbosum var. thompsoniae E. reniforme var. playanum, E. reniforme subsp. pusillum
Name authority S. Watson: Amer. Naturalist 7: 302. (1873) Torrey & A. Gray: Proc. Amer. Acad. Arts 8: 184. (1870)
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