Oxalis stricta L.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Perennial from long slender rhizomes, prostrate to more often erect and to 5 dm; stems pubescent with spreading, blunt-tipped, septate hairs, sometimes also strigose, seldom glabrous; stipules none; lfls 1–2 cm wide, usually glabrous to merely ciliate; peduncles usually exceeding the fls, 2–7-fld; pet 4–9 mm, yellow; fr 8–15 mm, provided with spreading, flexuous, septate hairs; 2n=18–24. Nearly cosmopolitan weed, often in natural habitats as well, probably originally native to N. Amer. Numerous infraspecific taxa are often defined on the distribution and orientation of the hairs. (O. europaea; O. corniculata, misapplied; Xanthoxalis stricta; X. bushii; X. cymosa; X. rufa)
common yellow wood-sorrel