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Thompson's buckwheat, Thompson's wild buckwheat

Siskiyou buckwheat, Siskiyou wild buckwheat

Habit Herbs, spreading, not scapose, 2–5(–6) × 2–5 dm, glabrous, green. Herbs, spreading, matted, 0.5–2 × 1–5 dm, glabrate or glabrous.
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 spreading;

aerial flowering stems erect, slender, solid, not fistulose, arising at nodes of caudex branches and at distal nodes of short, non-flowering aerial branches, 0.5–1.5(–2) dm, usually glabrous, with a whorl of 2–4 leaflike bracts ca. midlength, similar to leaf blade, 0.3–0.5 × 0.1–0.2 cm.

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.

in dense compact basal rosettes;

petiole 0.2–0.6 cm, glabrate or glabrous;

blade spatulate to round, (0.3–)0.5–0.8 × (0.2–)0.3–0.5(–0.7) cm, densely white to thinly tomentose abaxially, sparsely floccose to glabrate and green or olive green adaxially, rarely glabrous on both surfaces, margins entire, plane.

Inflorescences

cymose, open, 10–30 × 10–25 cm;

branches dichotomous, glabrous;

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

capitate, rarely umbellate, 0.8–1.5 cm wide or 1–2 × 1–3 cm;

branches usually glabrate;

bracts absent immediately below involucre.

Peduncles

absent.

Involucres

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

teeth 5, erect, 0.4–0.5 mm.

1 per node, turbinate-campanulate to campanulate, (3–)3.5–4 × 4–6 mm, arachnoid-tomentose;

teeth 6–10, lobelike, reflexed, (2–)2.5–3.5 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.

(4–)4.5–6 mm, including 0.6–1 mm stipelike base;

perianth sulphur yellow, glabrous;

tepals monomorphic, oblong;

stamens exserted, 3.5–5 mm;

filaments pilose proximally.

Achenes

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

light brown, 4.5–5 mm, glabrous.

Eriogonum thompsoniae

Eriogonum siskiyouense

Phenology Flowering Jul–Sep.
Habitat Gravelly serpentine slopes and outcrops, manzanita communities, montane conifer woodlands
Elevation 1600-2800 m (5200-9200 ft)
Distribution
from FNA
AZ; UT
[WildflowerSearch map]
[BONAP county map]
from FNA
CA
[BONAP county map]
Discussion

Varieties 3 (3 in the flora).

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

Eriogonum siskiyouense is restricted to the ridge system that extends from the Scott Mountain area to the Mt. Eddy region of Siskiyou and Trinity counties. The vast majority of individuals in a population have a single involucre atop each flowering stem, but at lower elevations and in somewhat more protected sites the inflorescence may be umbellate. The Siskiyou wild buckwheat does well in cultivation if its soil requirements are fulfilled.

(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. 356.
Parent taxa Polygonaceae > subfam. Eriogonoideae > Eriogonum > subg. Eucycla Polygonaceae > subfam. Eriogonoideae > Eriogonum > subg. Oligogonum
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. 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. 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. ursinum var. siskiyouense
Name authority S. Watson: Amer. Naturalist 7: 302. (1873) Small: Bull. Torrey Bot. Club 25: 44. (1898)
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