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Published In: Species Plantarum 1: 435. 1753. (1 May 1753) (Sp. Pl.) Name publication detailView in BotanicusView in Biodiversity Heritage Library

Project Name Data (Last Modified On 9/1/2017)
Acceptance : Accepted
Project Data     (Last Modified On 7/9/2009)
Status: Native


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4. Oxalis stricta L. (yellow wood sorrel)

O. stricta var. bushii (Small) Farw.

O. bushii Small

O. cymosa Small

O. europaea Jord.

O. europaea var. bushii (Small) Wiegand

O. europaea f. cymosa (Small) Wiegand

O. europaea f. pilosella Wiegand

O. europaea f. subglabrata Wiegand

O. europaea f. vestita Wiegand

O. europaea f. villicaulis Wiegand

O. fontana Bunge

O. fontana var. bushii (Small) H. Hara

Pl. 474 a, b; Map 2169

Plants annual or perennial, with taproots when young, but usually developing slender, white to pinkish-tinged rhizomes, these sometimes becoming thickened and blackish brown with age, lacking bulbs. Aerial stems 1(–3), 10–50(–90) cm long, variously erect or becoming prostrate, then not or rarely rooting at the nodes, sparsely to moderately pubescent with short, unicellular, appressed to upward-curved hairs and also at least a few (sometimes dense) relatively long, more or less spreading, slender, multicellular hairs (these often with reddish purple crosswalls), the pubescence sometimes denser near the stem tips, some of the hairs occasionally gland-tipped. Leaves basal (on young plants) and alternate, those on older stems often appearing fasciculate from the stem nodes, the petiole moderately to densely pubescent with appressed to strongly ascending hairs and often also sparse to dense, spreading, multicellular hairs. Stipules absent or, if present, then represented by slight thickenings or inconspicuous wings at the petiole base, these green. Leaflets (5–)8–30 mm long, obcordate, the apical notch to 1/3 of the total length, the upper surface usually glabrous, the surfaces sparsely to moderately pubescent with appressed to loosely appressed hairs, yellowish green to grayish green, usually lacking purplish to brownish markings. Inflorescences paniculate (with a central flower flanked by a pair of branches bearing 2 or more flowers), with 5–8(–15) total flowers, if rarely reduced to 3 flowers then the central flower sessile or much shorter-stalked than the outer pair. Sepals 2.5–6.0 mm long, oblong-lanceolate to narrowly oblong-elliptic, green or translucent at the tip. Petals 4–11 mm long, yellow. Fruits 8–20 mm long, cylindrical at maturity, variously glabrous to densely pubescent with short, appressed to more or less spreading, unicellular and/or multicellular hairs. Seeds 1.0–1.8 mm long, brown, the ridges often at least faintly grayish or whitened. 2n=18, 24. May–October.

Scattered nearly throughout the state (nearly throughout the U.S.; Canada, Mexico; introduced widely in the Old World). Bottomland forests, mesic to dry upland forests, savannas, upland prairies, glades, and banks of streams and rivers; also pastures, fallow fields, gardens, railroads, roadsides, and disturbed areas.

This is the most common species of yellow wood sorrel in the state and also forms the longest stems. Specimens with poorly developed inflorescences can easily be confused with O. dillenii. In cases where only three flowers are produced in the inflorescences, plants of O. stricta usually have the central flower sessile or relatively short-stalked and sometimes have an additional pair of bracts along one or both lateral branches. Collectors should also check for the presence of slender stolons, which are easily lost when a specimen is collected. As in other species of Oxalis, plants of O. stricta are quite variable morphologically. Particularly distinctive are populations in which plants have relatively robust, erect, unbranched stems that are densely pubescent with spreading multicellular hairs. However, as shown in Steyermark’s (1963) discussion, the stem pubescence character states do not correlate with variations in leaf, inflorescence, and sepal pubescence or degree of glandularity.

Oxalis illinoensis Schwegman is superficially similar to O. stricta in its relatively long, often erect stems, usual presence of multicellular hairs, relatively large leaves, and branched inflorescences. It differs from O. stricta in its larger flowers (corollas 12–18 mm long) and in the production of small white tubers along the rhizome. This species was described relatively recently (Schwegman, 1982) as a segregate of another large-flowered, but generally more eastern species, O. grandis Small, which lacks tubers, has more rounded, often purplish-tinged or -marked leaflets, and has less prominently red-marked petals. Oxalis illinoensis is endemic to a small region from southern Indiana to central Tennessee, west to southern Illinois and western Kentucky, where it occurs close to the Missouri border. Thus, Missouri botanists should search for populations of this large-flowered wood sorrel in the southeastern portion of the state.



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