Oxalis dillenii Jacq.
Yellow Wood Sorrel
CC = 0
CW = 3
MOC = 92
Family - Oxalidaceae
Stems - Multiple from the base, from fibrous roots, ascending, herbaceous, densely antrorse appressed pubescent, to +20cm tall, branching.
Leaves - Alternate, petiolate, trifoliolate. Petioles to +4cm long, with few to many antrorse appressed hairs. Leaflets obcordate, mostly sessile, antrorse appressed pubescent below, mostly glabrous adaxially, entire, to +/-1.5cm broad and long.
Inflorescence - Axillary pedunculate umbels of 2-6 flowers. Peduncles pubescent as the stems, to 6cm long. Umbels subtended by small linear bracts. Bracts to 3-4mm long. Pedicels erect in flower, spreading to slightly reflexed in fruit, to -2cm long, pubescent as the stems.
Flowers - Corolla yellow, deeply 5-lobed, glabrous. Lobes to 1.2cm long, 6mm broad, rounded to emarginate. Stamens 10, united at the base into a tube which surrounds the ovary. Filaments glabrous, yellowish, to 5mm long. Ovary 5-carpellate. Styles antrorse appressed pubescent, to 3mm long. Sepals 5, distinct, green, acute, antrorse appressed pubescent, oblong to linear-oblong, to 6mm long, 2mm broad, glabrous internally. Fruits erect, appressed and spreading pubescent, to 2.5cm long, with many seeds.
Flowering - May - November.
Habitat - Fields, glades, prairies, gravel bars, waste ground, roadsides, railroads.
Origin - Native to U.S.
Other info. - This little species can be found throughout Missouri. It is a very common "weed."
Photographs taken on Bear Mountain, MO., 6-1-03.