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Eriogonum microthecum var. ambiguum
YELLOW-FLOWERED WILD BUCKWHEAT

Higher Taxonomy
Family: PolygonaceaeView DescriptionDichotomous Key

Common Name: BUCKWHEAT FAMILY
Habit: Annual to shrub [tree]. Stem: nodes swollen or not. Leaf: simple, basal or cauline, generally alternate; ocreae present or 0, generally scarious, persistent or not. Inflorescence: flower clusters in axillary to terminal cyme-, panicle-, raceme-, spike-, umbel- or head-like arrangements, entire inflorescence or main inflorescence branches generally subtended by bracts ("inflorescence bracts"); peduncles present or 0; flower clusters in Eriogoneae-Eriogonoideae subtended by involucre of >= 1 free or +- fused, sometimes awn-tipped bracts ("involucre bracts") or, in Polygonoideae and rarely in Eriogonoideae, not (if bracts completely fused, involucre "tubular"); pedicels in Eriogoneae each often subtended by 2 free, transparent, linear bractlets or in Polygonoideae all subtended by 2+ fused, membranous, wide bractlets. Flower: generally bisexual, small, 1--200 per node; perianth parts 2--6, generally in 2 whorls, free or basally fused, generally petal-like, often +- concave adaxially, often darker at midvein, often turning +- red or +- brown in age; stamens [1]3 or 6--9 in 2 whorls; ovary superior, 1-chambered, ovule 1, styles 1--3. Fruit: achenes, included in or exserted from perianth, generally 3-angled, ovoid or elliptic, generally glabrous.
Genera In Family: 48 genera, +- 1200 species: worldwide, especially northern temperate; some cultivated for food (Coccoloba, sea-grape; Fagopyrum, Rheum, Rumex) or ornamental (Antigonon, lovechain; Coccoloba; Muehlenbeckia; Persicaria; Polygonum), a few timbered (Coccoloba; Triplaris). Several (Emex; Fallopia; Persicaria; Polygonum; Rumex) are weeds. Note: Treatment of genera in Eriogonoideae based on monographic work of James L. Reveal. Involucre number throughout is number (1--many) per ultimate grouping, at tips of ultimate branches; flower number is per flower cluster or involucre, unless otherwise stated. Fagopyrum esculentum Moench not naturalized, considered an historical waif (or garden weed +- presently), therefore not treated.
eFlora Treatment Author: Mihai Costea, except as noted
Scientific Editor: Thomas J. Rosatti, Bruce G. Baldwin.
Genus: EriogonumView DescriptionDichotomous Key

Common Name: WILD BUCKWHEAT
Habit: Annual to shrub, matted or not. Stem: prostrate to erect, occasionally 0, glabrous or hairy, occasionally glandular. Leaf: basal, sheathing (on stem above basal, beneath other, +- non-sheathing cauline), or cauline, alternate, opposite, or whorled; blades linear to +- round, generally longer than wide, margins flat, wavy, or rolled under; ocreae 0. Inflorescence: variable, glabrous or hairy, occasionally glandular; peduncles 0 or erect to reflexed (pointed down); involucres 1 or in clusters, tubular, glabrous or hairy, teeth generally 4--10, awns 0. Flower: (2)6--100(200), with a stalk-like base ("flower stipe" or "stipe") or not; perianth generally white to red or yellow, glabrous or hairy, occasionally glandular, lobes 6, generally entire; stamens 9. Fruit: generally brown or black, generally obconic, glabrous or hairy; embryo curved or straight.
Species In Genus: +- 250 species: temperate North America. Etymology: (Greek: woolly knees, for hairy nodes of 1st sp. named) Note: One of largest genera in California; stem in descriptions refers to the main stem(s), not branches of inflorescence. A perennial herb allied to Eriogonum austrinum (S. Stokes) Reveal and Eriogonum moranii Reveal of east-central Baja California, with spreading (rather than reflexed or erect) involucres on peduncles < 2 mm, occurring in DMtns (Bristol, Granite mountains), has been known for nearly 25 years yet remains undescribed. Eriogonum puberulum moved to Johanneshowellia.
eFlora Treatment Author: James L. Reveal & Thomas J. Rosatti
Species: Eriogonum microthecumView Description 

Habit: Subshrub or shrub, 0.2--1.5 dm, (0.6)1--13(16) dm diam. Stem: 0.05--1.5 dm, 0.1--1 dm, generally tomentose or glabrous. Leaf: cauline, blades (0.3)1--3.5 cm, (0.07)0.1--1.2 cm wide, linear to narrow, tomentose abaxially, less so or glabrous adaxially, margin occasionally rolled under. Inflorescence: 0.5--6(12) cm, 1--10(13) cm wide; branches tomentose to hairy or glabrous; peduncles 0 or generally erect, 0.3--1.5 cm, slender, tomentose to hairy; involucres (1.5)2--3.5(4) mm, 1.3--2.5(3) mm wide, tomentose to hairy or glabrous. Flower: 1.5--3(4) mm, glabrous; perianth yellow or white to pink, orange, rose, red (or cream), lobes oblong to obovate. Fruit: 1.5--3 mm, glabrous.
Note: Other varieties in Oregon, Idaho, Nevada, Utah.

Eriogonum microthecum var. ambiguum (M.E. Jones) Reveal
NATIVE
Habit: Subshrub or shrub, 0.5--5 dm, 1--8 dm diam. Stem: 0.2--1 dm, generally hairy. Leaf: blades 0.8--2.5 cm, (0.2)0.3--0.6(0.8) cm wide, tomentose abaxially, hairy adaxially. Inflorescence: 1--5(12) cm; branches tomentose to hairy; involucres 2--2.5 mm, tomentose to hairy. Flower: (1.5)2--2.5(3) mm; perianth yellow. Fruit: 1.5--2 mm.
Ecology: Common. Sand, gravel or rocks; Elevation: (1100)1900--3300 m. Bioregional Distribution: SNH (e slope), GB; Distribution Outside California: to southeastern Oregon, southwestern Idaho, western Nevada. Flowering Time: Jul--Sep
Synonyms: Eriogonum aureum M.E. Jones var. ambiguum M.E. Jones; Eriogonum fruticosum A. Nelson var. ambiguum (M.E. Jones) A. Nelson; Eriogonum microthecum Nutt. var. expansum S. Stokes; Eriogonum tenellum Torr. var. erianthum Gand.
eFlora Treatment Author: James L. Reveal & Thomas J. Rosatti
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Citation for this treatment: James L. Reveal & Thomas J. Rosatti 2016. Eriogonum microthecum var. ambiguum, in Jepson Flora Project (eds.) Jepson eFlora, http://ucjeps.berkeley.edu/cgi-bin/get_IJM.pl?tid=58632, accessed on February 13, 2016.

Citation for the whole project: Jepson Flora Project (eds.) 2016. Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html, accessed on February 13, 2016.


Eriogonum microthecum var. ambiguum
click for enlargement
© 2007 Steve Matson
Eriogonum microthecum var. ambiguum
click for enlargement
© 2006 Aaron Schusteff
Eriogonum microthecum var. ambiguum
click for enlargement
© 2006 Steve Matson
Eriogonum microthecum var. ambiguum
click for enlargement
© 2006 Aaron Schusteff
Eriogonum microthecum var. ambiguum
click for enlargement
© 2006 Steve Matson
Eriogonum microthecum var. ambiguum
click for enlargement
© 2005 Steve Matson

More photos of Eriogonum microthecum var. ambiguum in CalPhotos


Geographic subdivisions for Eriogonum microthecum var. ambiguum:
SNH (e slope), GB;
Markers link to CCH specimen records. If the markers are obscured, reload the page [or change window size and reload]. Yellow markers indicate records that may provide evidence for eFlora range revision or may have georeferencing or identification issues.
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map of distribution 1
(Note: any qualifiers in the taxon distribution description, such as 'northern', 'southern', 'adjacent' etc., are not reflected in the map above, and in some cases indication of a taxon in a subdivision is based on a single collection or author-verified occurence).

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Duplicates counted once; synonyms included.
Species do not include records of infraspecific taxa.
Blue line denotes eFlora flowering time.