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FNA | Family List | FNA Vol. 5 | Polygonaceae | Eriogonum

1h. Eriogonum Michaux subg. Oregonium (S. Watson) Greene, Fl. Francisc. 146. 1891.

Eriogonum [unranked] Oregonium S. Watson, Proc. Amer. Acad. Arts 12: 262. 1877

Herbs, spreading to erect or prostrate, rarely decumbent annuals, glabrous or floccose to tomentose or lanate, sometimes sericeous puberulent, or short-pilose; taproot not woody. Stems prostrate, ascending or erect, without persistent leaf bases, lanate, tomentose, floccose, or glabrous, sometimes sericeous, puberulent, or short-pilose; caudex absent; aerial flowering stems prostrate to ascending or erect, slender to stout, solid, not fistulose, not disarticulating in ringlike segments proximally, arising directly from root. Leaves persistent or marcescent, basal, cauline, or basal and cauline, 1 per node not fasciculate; blade tomentose to floccose or glabrous, sometimes sericeous, puberulent, or short-pilose, not glandular. Inflorescences cymose, open or diffuse; bracts 3, connate basally, scalelike. Peduncles usually absent, when present restricted to proximal nodes, erect, straight, slender. Involucres 1 per node, usually appressed to the inflorescence branches, cylindric to turbinate or rarely campanulate; teeth 5, rarely 6-8, erect or rarely spreading, rarely lobelike, spreading to somewhat reflexed and dividing involucral tube nearly to base. Flowers abruptly narrowing to acute base on slender pedicel, without stipelike base; perianth cream, white to pink or rose, yellow, or red, rarely ochroleucous, usually glabrous or glandular, sometimes hispid, hispidulous, pubescent, or hirtellous abaxially, occasionally papillose, mostly glabrous adaxially; tepals connate proximally 4- 2 their length, monomorphic or dimorphic; stamens included or exserted; filaments glabrous or pilose proximally. Achenes light to dark brown or rarely nearly black, not winged, lenticular to more often 3-gonous, glabrous. Seeds: embryo curved.

Species 28 (26 in the flora): w North America including n Mexico, mainly California.

The species of Eriogonum subg. Oregonium not treated here are E. foliosum S. Watson and E. hastatum Wiggins; they occur in northern Mexico.

1 Involucres terminal at tips of short branchlets proximally, not appressed to branches; peduncles sometimes present   (2)
+ Involucres not terminal at tips of short branchlets proximally, usually appressed to branches; peduncles absent   (11)
2 (1) Flowers 0.7-1.5 mm; perianth yellow or cream; arid regions of e and se California, wc Nevada   (3)
+ Flowers 1-2.5(-3) mm; perianth yellow or white to pink, rose, or red; Coast Ranges and w Sierra Nevada, California   (4)
3 (2) Perianths yellow; flowers 0.7-1 mm; inflorescences diffuse, spreading; Mojave Desert, se Kern, ne Los Angeles, and nw San Bernardino counties, California   199 Eriogonum mohavense
+ Perianths cream; flowers 1-1.5 mm; inflorescences narrow; Great Basin, s Mono and n Inyo counties, California, w Mineral and Esmeralda counties, Nevada   200 Eriogonum ampullaceum
4 (2) Stems glabrous; involucres sessile or, if short-pedunculate, plants from western foothills of Sierra Nevada, California   (5)
+ Stems tomentose or, if glabrous, involucres pedunculate at proximal nodes and plants from Coast Ranges of California   (7)
5 (4) Basal leaf blades oblong-ovate, reniform, or rounded to cordate; involucres 3-4 mm, 5-toothed; n California from San Mateo, Santa Clara, and Mariposa counties n to sw and sc Oregon   208 Eriogonum luteolum (in part)
+ Basal leaf blades suborbiculate or round to reniform; involucres 2-4 mm, 5-8-toothed; wc California from Santa Clara and Stanislaus counties s to Santa Barbara and Ventura counties   (6)
6 (5) Involucres 2-2.5 mm; 5-toothed; flowers 2-2.5(-3) mm, perianth minutely puberulent, white to rose or yellow in fruit; Santa Clara and Stanislaus counties s to w Kern and nw Ventura counties, California   206 Eriogonum covilleanum
+ Involucres 3-4 mm; 6-8-toothed; flowers 1-2 mm, perianth glabrous, white to rose in fruit; c Monterey and w San Benito counties, California   207 Eriogonum nortonii
7 (4) Involucres glabrous; e Monterey, w San Benito, and s Santa Clara (extirpated) counties, California   205 Eriogonum argillosum
+ Involucres tomentose; Contra Costa, Fresno, Kern, Merced, Monterey, San Benito, San Luis Obispo, and Solano counties, California   (8)
8 (7) Leaves strictly basal, blade suborbiculate; styles 0.1-0.3 mm; sw Fresno County, California   201 Eriogonum eastwoodianum
+ Leaves basal and subbasal, or basal and cauline, suborbiculate or narrowly oblong to ovate; styles 0.2-1 mm; Contra Costa, Fresno, Kern, Merced, Monterey, San Benito, San Luis Obispo, and Solano counties, California   (9)
9 (8) Involucres 2.5-3.5(-4) mm; styles 0.2-0.3 mm; e Contra Costa and s Solano counties, California (extinct)   204 Eriogonum truncatum
+ Involucres (1.5-)1.8-2.5 mm; styles 0.2-1 mm; Fresno, Kern, Merced Monterey, San Benito, and San Luis Obispo counties, California   (10)
10 (9) Perianths not pustulose; achene beaks granular; involucres 2-2.5 mm; leaves basal and subbasal, rarely cauline; nw Kern, se Monterey, and ne San Luis Obispo counties, California   202 Eriogonum temblorense
+ Perianths pustulose; achene beaks papillose; involucres (1.5-)1.8-2 mm; leaves basal and often cauline; w Fresno, sw Merced, and se San Benito counties, California   203 Eriogonum vestitum
11 (1) Leaf blades puberulent to short-pilose or sericeous; flowering stems and inflorescence branches puberulent to short-pilose or sericeous   (12)
+ Leaf blades tomentose at least abaxially; flowering stems and inflorescence branches glabrous or tomentose to floccose or lanate   (13)
12 (11) Outer tepals oblong-lanceolate to oblong-ovate; plants puberulent to short-pilose; n Arizona, nw and sw Colorado, nw New Mexico, e and wc Utah, sw Wyoming   223 Eriogonum divaricatum
+ Outer tepals fan-shaped and hooded; plants sericeous; nw Arizona, se Nevada, sc Utah   224 Eriogonum darrovii
13 (11) Perianths densely pubescent, white to rose; nw California   222 Eriogonum dasyanthemum
+ Perianths glabrous or sparsely glandular, not densely hairy, white, creamy white, yellow, rose, or red; widespread   (14)
14 (13) Involucres (1.8-)2-5(-7) mm; outer tepals not fan-shaped   (15)
+ Involucres 1-1.5 mm or, if 2 mm, outer tepals fan-shaped or slightly hastate proximally and plants primarily of Great Basin and warm desert regions   (21)
15 (14) Leaf blades oblong-obovate to oblanceolate or oblong; flowering stems and inflorescence branches lanate to tomentose or floccose or, if glabrous, plants not of central Sierra Nevada   (16)
+ Leaf blades round-ovate to rounded, reniform, or nearly so or, if not, inflorescence branches glabrous and plants of Sierra Nevada; flowering stems and inflorescence branches glabrous or tomentose to floccose   (18)
16 (15) Involucres (3.5-)4-5 mm, cylindric; outer tepals narrowly obovate to oblong; achenes 1.8-2(-2.2) mm; California and sw Oregon   212 Eriogonum roseum
+ Involucres (1.8-)2-3 mm, turbinate; outer tepals lanceolate to oblong or oblong-obovate; achenes 1-2 mm; California   (17)
17 (16) Inflorescence branches straight; basal leaf blades oblanceolate to oblong, (0.8-)1-4(-6) cm, petiole not winged; involucres (1.8-)2-3 mm; flowers 1.5-3 mm; perianth white to pink or yellow; California   213 Eriogonum gracile
+ Inflorescence branches upwardly curved; basal leaf blades oblanceolate or elliptic to ovate or nearly rounded, 1-2 cm, petiole occasionally winged; involucres 2.5-3 mm; flowers 1.5-2 mm, perianth white to rose; sw California   214 Eriogonum cithariforme
18 (15) Inflorescence branches floccose, especially proximally; leaves basal; perianths white to rose or pale yellow; nw California, w Idaho, n Nevada, c and e Oregon, se Washington   209 Eriogonum vimineum
+ Inflorescence branches glabrous or occasionally tomentose, or if floccose then leaves basal and cauline; stems usually 1; perianths white to pink, red, or yellow; California   (19)
19 (18) Involucres (3.5-)4-5(-7) mm; plants 4-10 dm; s California   211 Eriogonum molestum
+ Involucres 2-4 mm; plants 1-5 dm; California n to Oregon, e to Arizona and Utah   (20)
20 (19) Leaves basal and cauline, involucres 3-3.5 mm, and flowers 1.5-2 mm on floccose inflorescence branches or, if leaves strictly basal and stems glabrous, involucres 2-3.5 mm and plants of foothills and mid-elevation of central Sierra Nevada; perianths white to rose; n California   208 Eriogonum luteolum (in part)
+ Leaves basal; involucres 3-4 mm; flowers 1.5-2 mm; perianth white to pink or red, rarely yellow; flowering stems glabrous; w Arizona, s California, s Nevada, s Utah   210 Eriogonum davidsonii
21 (14) Stems glabrous or, if tomentose, then flowers glandular and plants of eastern slope of Sierra Nevada and Great Basin; outer tepals oblong to oblong-obovate   (22)
+ Stems tomentose to floccose; outer tepals narrowly to broadly fan-shaped or slightly hastate proximally   (24)
22 (21) Perianths yellow or pale yellowish, rarely whitish; flowers 0.6-0.8(-1) mm;e California, w Nevada, sc Oregon   217 Eriogonum brachyanthum
+ Perianths white to rose; flowers 1-2 mm; e and s California, sc Idaho, Nevada, e Oregon, sw Utah, e Washington   (23)
23 (22) Flowers 1.5-2 mm; perianths usually minutely glandular, rarely glabrous; flowering stems and inflorescence branches glabrous or tomentose; e and s California, sc Idaho, Nevada, e Oregon, sw Utah, e Washington   215 Eriogonum baileyi
+ Flowers 1-1.5 mm; perianths glabrous; flowering stems and inflorescence branches glabrous; sw California   216 Eriogonum elegans
24 (21) Outer tepals slightly hastate proximally in fruit; flowers 0.8-1.2 mm; involucres campanulate, 1-2 mm; montane habitats; c Riverside, w San Bernardino, and nc San Diego counties, California (presumed extinct)   218 Eriogonum evanidum
+ Outer tepals fan-shaped; flowers 1-3.5 mm; involucres 1-2.5 mm; desert habitats; not of c Riverside, w San Bernardino, and nc San Diego counties, California   (25)
25 (24) Leaves cauline; leaf blades narrowly oblanceolate to broadly elliptic; plants narrowly erect, (0.5-)1-6 dm; perianths white, becoming pink or red; c and s Arizona, se California (presumed extirpated), w and s New Mexico, w Texas, s Utah   221 Eriogonum polycladon
+ Leaves basal; leaf blades suborbiculate or rounded to cordate; plants usually spreading, 0.5-1.5(-3) dm; perianths white to pink or pale yellow to yellow, rarely creamy white, becoming pink or red; widespread   (26)
26 (25) Perianths pale yellow or yellow, rarely creamy white, becoming red; outer tepals broadly fan-shaped; inflorescences diffuse, branches inwardly curved distally; achenes 1-1.3 mm; nw Arizona, e California, sw Idaho, Nevada, se Oregon, sw Utah   219 Eriogonum nidularium
+ Perianths white to pink or pale yellowish, outer tepals narrowly fan-shaped; inflorescences open, branches not inwardly curved distally; achenes 1.5-1.8 mm; Arizona, e California, nw and sw Colorado, sw Idaho, Nevada, w New Mexico, Utah   220 Eriogonum palmerianum


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