Flora of North America species comparison

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Oxalis oregana

Oxalis stricta

Oregon oxalis, Oregon wood-sorrel, red wood-sorrel

common yellow oxalis, common yellow wood sorrel, European wood-sorrel, upright yellow oxalis, upright yellow wood-sorrel, yellow woodsorrel
Habit Herbs perennial, acaulous, rhizomes present, fleshy-thickened, densely scaly, stolons absent, bulbs absent. Herbs annual or short-lived perennial, caulescent, rhizomes present, short, stolons absent, bulbs absent.
Aerial stems

1(–3) from base, erect or later leaning or falling over and decumbent, not rooting at nodes, 20–60(–90) cm, herbaceous, villous, hairs ± straight, spreading, usually nonseptate and septate, septate hairs commonly concentrated at nodes, very rarely only nonseptate.
Leaves

basal, clustered at rhizome tips;

petiole 5–15(–21) cm, sparsely to densely villous, hairs rusty;

leaflets 3, green, broadly obcordate, 10–30(–40) mm, lobed 1/5–1/4 length, lobes apically convex, surfaces sparsely villous, oxalate deposits absent.

basal and cauline;

stipules rudimentary;

petiole 2–8 cm, hairs septate and nonseptate;

leaflets 3, light green to yellowish green, obcordate, (8–)10–20(–30) mm, lobed 1/5–1/3 length, surfaces glabrous, oxalate deposits absent.
Inflorescences

1-flowered;

scapes (6–)11–25 cm, glabrous or sparsely villous.

usually regular cymes, rarely irregular cymes, (1–)5–7(–15)-flowered;

peduncles 3–9(–11) cm.
Flowers

heterostylous;

sepal apices without tubercles;

petals white to deep pink, usually with yellow spot sub-basally and prominent purple veins, (8–)15–25 mm.

homostylous or slightly to strongly heterostylous, usually within or slightly above level of leaves;

sepal apices without tubercles;

petals yellow, without red lines, (6–)8–11 mm.
Capsules

ovoid, 6–8(–12) mm, glabrate.

± cylindric, nearly terete, abruptly tapering to apex, 8–15 mm, villous to puberulent or glabrate, hairs septate.
Seeds

brown, transverse ridges rarely white.
2n

= 18, 24.

Oxalis oregana

Oxalis stricta
Phenology Flowering Feb–Sep. Flowering (Apr–)Jul–Oct.
Habitat Douglas fir, mixed fir, cedar-spruce, mixed conifer, and hemlock-maple forests, maple woodlands, alder glens, Gaultheria thickets, stream banks. Prairie ravines, riverbanks, sandbars, low woods, mesic forests, floodplains, roadsides, fields, lawns, gardens.
Elevation 10–800(–1000) m. (0–2600(–3300) ft.) 20–1200 m. (100–3900 ft.)
Distribution
from FNA
CA; OR; WA; BC
[WildflowerSearch map]
[BONAP county map]
from FNA
AL; AR; AZ; CO; CT; DC; DE; GA; IA; ID; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; MT; NC; ND; NE; NH; NJ; NM; NY; OH; OK; PA; RI; SC; SD; TN; VA; VT; WA; WI; WV; WY; BC; MB; NB; NF; NS; ON; PE; QC; SK [Introduced in Europe, Asia, Africa, Pacific Islands (New Zealand), Australia]
[WildflowerSearch map]
[BONAP county map]
Discussion

Oxalis oregana has sometimes been treated as a disjunct geographical taxon of the European O. acetosella Linnaeus (see comments under 21. O. montana).

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

Oxalis stricta is uncommon and probably adventive in Canada and the western United States. The species is recognized by the combination of its tall (rarely up to nearly a meter), erect stems from a short, simple rhizome; septate hairs; cymose inflorescence; and small flowers. Septate hairs on the stems and petioles are easily recognized (lens) by their colored cross-walls, but they vary greatly in density. In villicaulis forms, the hairs are dense and evenly distributed, but in most plants over the range they are localized around the nodes and intermixed with nonseptate hairs. Often they are sparse; rarely they appear to be absent on plants with greatly reduced vestiture overall.

A. Lourteig (1979) identified this species as Oxalis fontana, typified by a plant from northern China, and applied the name O. stricta to the species identified by G. Eiten (1955, 1963) and here as O. dillenii. The basis for the difference lies in selection of lectotypes. Choice of stricta as the correct epithet acknowledges that the description of O. stricta by Linnaeus best matches these plants and that selection of a Morison illustration as lectotype characterizes the species long-naturalized and weedy in Europe and probably known first-hand by Linnaeus. C. E. Jarvis (2007) has confirmed this choice of lectotype. Oxalis dillenii is appropriately lectotypified by a John Clayton collection from Virginia. The situation has been summarized well by D. B. Ward (2004).

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 12, p. 148. FNA vol. 12, p. 143.
Parent taxa Oxalidaceae > Oxalis Oxalidaceae > Oxalis
Sibling taxa
O. albicans, O. articulata, O. bowiei, O. brasiliensis, O. caerulea, O. californica, O. colorea, O. corniculata, O. debilis, O. decaphylla, O. dichondrifolia, O. dillenii, O. drummondii, O. florida, O. frutescens, O. grandis, O. hirta, O. hispidula, O. illinoensis, O. incarnata, O. intermedia, O. latifolia, O. laxa, O. macrantha, O. metcalfei, O. montana, O. pes-caprae, O. pilosa, O. purpurea, O. stricta, O. suksdorfii, O. texana, O. triangularis, O. trilliifolia, O. violacea
O. albicans, O. articulata, O. bowiei, O. brasiliensis, O. caerulea, O. californica, O. colorea, O. corniculata, O. debilis, O. decaphylla, O. dichondrifolia, O. dillenii, O. drummondii, O. florida, O. frutescens, O. grandis, O. hirta, O. hispidula, O. illinoensis, O. incarnata, O. intermedia, O. latifolia, O. laxa, O. macrantha, O. metcalfei, O. montana, O. oregana, O. pes-caprae, O. pilosa, O. purpurea, O. suksdorfii, O. texana, O. triangularis, O. trilliifolia, O. violacea
Synonyms O. acetosella subsp. oregana, O. oregana var. smalliana, O. oregana var. tracyi, O. smalliana O. bushii, O. coloradensis, O. cymosa, O. europaea, O. europaea var. bushii, O. fontana, O. fontana var. bushii, O. interior, O. rufa, O. stricta var. decumbens, O. stricta var. piletocarpa, O. stricta var. rufa, O. stricta var. villicaulis, Xanthoxalis bushii, X. cymosa, X. rufa, X. stricta
Name authority Nuttall: in J. Torrey and A. Gray, Fl. N. Amer. 1: 211. (1838) Linnaeus: Sp. Pl. 1: 435. (1753)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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