Oxalis pes-caprae
Oxalis dillenii
African wood-sorrel, Bermuda buttercup, soursob
common yellow wood-sorrel, Dillen's oxalis, graygreen sorrel, slender yellow wood-sorrel, southern yellow wood-sorrel
(1–)2–8 from base, erect initially, often becoming decumbent or prostrate and stolonlike, rarely rooting at nodes, 10–25 cm, usually herbaceous, sometimes becoming woody proximally, densely and evenly strigillose to strigose from base to peduncles and pedicels, hairs straight, antrorsely appressed, nonseptate, sharp-pointed.
basal, rarely absent at flowering;
petiole 3–12 cm;
leaflets 3, green, rarely mottled with purplish red spots, angular-obcordate, (5–)7–20 mm, lobed 1/4–2/5 length, lobes apically convex, margins and abaxial surface villous, adaxial surface glabrous, oxalate deposits absent.
basal and cauline;
stipules oblong, margins narrowly flanged or without free portions, apical auricles absent;
petiole 1–4 cm, hairs nonseptate;
leaflets 3, green, obcordate, (4–)6–15(–21) mm, lobed 1/5–1/3 length, abaxial surface sparsely strigillose, adaxial surface glabrous, oxalate deposits absent.
umbelliform cymes, 2–12(–20)-flowered;
scapes often becoming fistulose proximally, 15–30 cm, sparsely villous to pilose.
usually umbelliform cymes, rarely irregular cymes, 1–3(–8)-flowered;
peduncles 1–6(–10) cm.
tristylous in diploids and tetraploids, consistently short-styled in pentaploids;
sepal apices with 2 orange tubercles;
petals deep golden yellow, 15–20 mm.
mostly homostylous;
sepal apices without tubercles;
petals yellow, without red lines, (2.5–)4–8 mm.
not seen.
angular-cylindric, abruptly tapering to apex, 12–20(–25) mm, densely strigose-pilose, hairs both appressed and spreading, with puberulent understory.
brown, transverse ridges with strong grayish or white lines.
= 14, 28, 35.
= 18, 20, 22, 24.
Oxalis pes-caprae
Oxalis dillenii
Outside its native range, Oxalis pes-caprae is mostly represented by a sterile pentaploid morph, although tetraploids also are known. The occurrence of both pentaploid and tetraploid individuals in the exotic range may be the result of independent introductions (P. Michael 1964; R. Ornduff 1986). Fruit production has not been observed in North America, and the plants are assumed to be seed-sterile (Ornduff 1987). Bulbs of O. pes-caprae are rarely collected, as they detach easily from the vertical, rootlike stems. Each bulb may produce over 20, small, whitish bulblets each year. Bulblets may also be formed at the soil surface crown.
Oxalis pes-caprae was reported by J. K. Small (1933) to occur in waste places and cultivated grounds in northern Florida, but as noted by D. B. Ward (2004), no Florida specimens are known.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Decumbent stems of Oxalis dillenii often appear stolonlike, producing erect branches and leaves at the nodes, rarely producing a few adventitious roots. Such plants sometimes are misidentified as O. corniculata, but they differ in their overall habit, stems and rhizomes that become woody, reduced stipules, strigillose cauline vestiture, denser fruit vestiture, and seed color. Plants of O. dillenii in Canada and the western United States appear to be adventive.
Plants of Oxalis dillenii flowering into November and December in Texas and North Carolina, and probably elsewhere, characteristically are depressed in habit, with creeping stems and forming matlike colonies. The corollas are small, with petals 2.5–3 mm. Although similar in habit to typical O. corniculata, these plants do not have stems that root at nodes, and the strigillose vestiture, though reduced in density, and the stipule morphology are like O. dillenii. Whether these are the same genotype as spring-flowering plants or a different entity remains to be investigated. At least some of the variability in O. dillenii, particularly in habit, may be genetically partitioned, as dysploid chromosome races apparently exist.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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