This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol2", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Oxalis filipes Small, in Britt. & Brown, 111. Fl. Ed. 1.
2: 349. 1897. Xanthoxalis filipes Small, Fl. SE. U. S. 667. 1903.
Plants bright green, very slender, sparsely pubescent with appressed hairs. Stem erect or decumbent, nearly simple, usually very leafy, wiry, 10'-2° high; leaves i'-ą wide, long-petioled, not stipulate, or the stipules represented by a narrow dilation of the base of the petiole; leaflets obcordate, with unequal sides, peduncles slender, equalling or exceeding the leaves, mostly I-flowered; flowers yellow; pedicels very slender, strigillose or glabrate, recurved in mature fruit; sepals oblong-lanceolate, 2"long, obtuse, with a tuft of hairs at the apex; petals 4" long, emarginate; capsule 4"-6" long, gradually narrowed to the apex, often curved.
Oxalis Brittoniae Small, in Britton, Man. 577.
1901. X. Brittoniae Small, Fl. SE. U. S. 668. 1903.
Plants often stoutish, loosely pubescent, bright green. Stem sparingly leafy, 4'-16' tall, often branched; leaves mostly 1/2'-3/4' broad; petioles filiform, sparingly villous; leaflets broader than long, nearly glabrous; peduncles about twice as long as their subtending petioles; cymes dichotomous or the primary branches suppressed, thus more umbel-like; sepals elliptic to narrowly oblong, 1 1/2"-2" long; corolla light yellow, 5" - 7 1/2" wide; filaments glabrous; styles glabrous; capsules columnar, abruptly acuminate, 7"-10" long.
X. interior Small, Fl. SE. U. S. 668. 1903.
Stems usually solitary, 1°-2° tall, hirsute; leaflets bright green throughout, 10"-15" wide, or some of them smaller, copiously strigillose, somewhat ciliate; cymes normally dichotomous, with some of the branches more or less suppressed, commonly raised above the leaves by the elongating peduncles; pedicels strigillose; sepals oblong to oblong-lanceolate, about 2" long, ciliate at the tip; petals 3"-4 1/2' long, light yellow; longer filaments sparingly ciliate above; capsules rather slender, 4"-s" long, on erect or ascending pedicels.
In woods and on partly shaded hillsides, Missouri and Arkansas. July-Oct.