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Thompson's buckwheat, Thompson's wild buckwheat

slender buckwheat, slender woolly buckwheat, slender woolly wild buckwheat

Habit Herbs, spreading, not scapose, 2–5(–6) × 2–5 dm, glabrous, green. Herbs, erect to spreading or somewhat decumbent, (0.7–)1.5–5(–7) dm, lanate to tomentose or floccose, rarely glabrous, greenish to whitish or grayish.
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.

aerial flowering stems erect, 0.5–2 dm, lanate to tomentose or floccose, rarely glabrous.

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 and cauline;

basal: petiole 1–4 cm, floccose, not winged, blade oblanceolate to oblong, (0.8–)1–4(–6) × 0.5–2 cm, tomentose abaxially, less so to floccose and greenish to grayish adaxially;

cauline: petiole 0.3–2 cm, floccose, blade oblanceolate, 0.5–3 × 0.3–1.5 cm, similar to basal blade.

Inflorescences

cymose, open, 10–30 × 10–25 cm;

branches dichotomous, glabrous;

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

cymose, occasionally distally uniparous due to suppression of secondary branches, open to somewhat diffuse, 0.5–4 × 0.5–3 cm;

branches lanate to tomentose or floccose, rarely glabrous, straight or nearly so, not inwardly curved distally;

bracts 0.5–3 × 1–3 mm.

Peduncles

absent.

absent.

Involucres

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

teeth 5, erect, 0.4–0.5 mm.

somewhat appressed to branches, turbinate, (1.8–)2–3 × 1.5–2 mm, floccose or glabrous;

teeth 5, erect, 0.3–0.6 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.

1.5–3 mm;

perianth white to pink or yellow, glabrous;

tepals monomorphic, lanceolate to oblong;

stamens mostly included, 1–1.5 mm;

filaments pilose proximally.

Achenes

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

brown, 3-gonous, 1–2 mm.

2n

= 22.

Eriogonum thompsoniae

Eriogonum gracile

Distribution
from FNA
AZ; UT
[WildflowerSearch map]
[BONAP county map]
from FNA
CA; Mexico
[WildflowerSearch map]
[BONAP county map]
Discussion

Varieties 3 (3 in the flora).

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

Varieties 2 (2 in the flora).

Eriogonum gracile is a highly variable species. The low, spreading plants from the mountains of coastal central California with 2–3 mm involucres and (usually) yellowish flowers differ from the more erect plants represented by the type collection, which have 1.8–2 mm involucres and white flowers. Such plants are found mainly farther south, in the Mt. Diablo and Mt. Hamilton areas of Alameda, Contra Costa, and Stanislaus counties. Some populations of E. gracile from the Inner Coast Ranges of eastern San Luis Obispo County are slightly different from the norm and the epithet leucocladon has been adopted in some local floristic treatments to account for them. However, the type of E. leucocladon does not seem to be this phase.

(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
1. Inflorescence branches lanate to tomentose or floccose; throughout California
var. gracile
1. Inflorescence branches glabrous; s California
var. incultum
Source FNA vol. 5, p. 261. FNA vol. 5, p. 423.
Parent taxa Polygonaceae > subfam. Eriogonoideae > Eriogonum > subg. Eucycla Polygonaceae > subfam. Eriogonoideae > Eriogonum > subg. Oregonium
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. 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. thompsoniae var. albiflorum, E. thompsoniae var. atwoodii, E. thompsoniae var. thompsoniae
E. gracile var. gracile, E. gracile var. incultum
Synonyms E. corymbosum var. thompsoniae E. vimineum subsp. gracile
Name authority S. Watson: Amer. Naturalist 7: 302. (1873) Bentham: Bot. Voy. Sulphur, 46. (1844)
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