Oxalis dillenii
Oxalis macrantha
common yellow wood-sorrel, Dillen's oxalis, graygreen sorrel, slender yellow wood-sorrel, southern yellow wood-sorrel
Price's 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.
usually 2–8 from base, erect initially, usually becoming decumbent, 5–20(–40) cm, becoming woody proximally, hirsute-pilose on at least proximal 2/3, hairs curved, loosely and irregularly spreading, nonseptate.
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.
basal and cauline;
stipules oblong, margins narrowly flanged or without free portions, apical auricles absent;
petiole 2–7 cm;
leaflets 3, green, obcordate, 3.5–12 mm, lobed 1/5–1/3 length, surfaces usually strigose-hirsute, sometimes glabrate, oxalate deposits absent.
usually umbelliform cymes, rarely irregular cymes, 1–3(–8)-flowered;
peduncles 1–6(–10) cm.
umbelliform cymes, less commonly irregular cymes, (1–)3–8-flowered;
peduncles (3–)5–10(–15) cm.
villous, hairs long, spreading.
mostly homostylous;
sepal apices without tubercles;
petals yellow, without red lines, (2.5–)4–8 mm.
distylous, well above level of leaves;
sepal apices without tubercles;
petals yellow to yellow-orange, with prominent red lines proximally, (13–)15–20(–23) mm.
angular-cylindric, abruptly tapering to apex, 12–20(–25) mm, densely strigose-pilose, hairs both appressed and spreading, with puberulent understory.
angular-cylindric, abruptly tapering to apex, 10–15 mm, sparsely to densely hirsute-pilose, hairs long, sometimes mostly along angles.
brown, transverse ridges with strong grayish or white lines.
brown, transverse ridges usually white.
= 18, 20, 22, 24.
Oxalis dillenii
Oxalis macrantha
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.)
Oxalis macrantha is restricted mostly to limestone glades in Alabama, Kentucky, and Tennessee. It is recognized by its villous to villous-hirsute stems, flowers in umbelliform cymes, and large yellow to yellow-orange corollas with red lines proximally. The lines in the throat remain visible after drying and usually can be seen on herbarium specimens even from the outside of the flower. A similar pattern also occurs in other species, especially O. grandis, O. illinoensis, and O. texana.
Seemingly disjunct plants of native habitats in Nuevo León, Mexico, identified as Oxalis macrantha apparently are more common than reported by G. L. Nesom (2009b). Whether these are actually disjunct or a parallel morphological expression derived from some Mexican species needs to be investigated.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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