Oxalis stricta L.
Oxalis, common yellow woodsorrel, common yellow oxalis, yellow wood-sorrel, common yellow wood-sorrel
|Kingdom||Plantae||Plants, but not fungi, lichens, or algae|
|Subkingdom||Tracheobionta||Vascular plants—plants with a “circulatory system” for delivering water and nutrients|
|Division||Magnoliophyta||Flowering plants, also known as angiosperms|
|Class||Magnoliopsida||Dicotyledons—plants with two initial seed leaves|
|Subclass||Rosidae||Roses, legumes, proteas, dogwoods, hydrangeas, mistletoes, euphorbias, grapes, many more|
|Order||Geraniales||Balsams, mustards, geraniums, wood sorrels, nasturtiums, others|
|Genus||Oxalis||Wood sorrels (Oxalis means “sour”)|
About plant names...
Oxalis is widespread in North America, though it is not known whether it is native or
introduced from Europe. It prefers open woodlands, meadows, lawns, gardens, disturbed areas, and sunny waste areas.
Plants: 3-8" (7.6-20 cm) tall, rarely reaching 12" (30 cm). Heavily
branched, especially near the base. Stems are light green and smooth, or covered with short appressed hairs,
lying flat against the stems. Younger plants may be hairier.
Leaves: Alternate, trifoliate, cloverlike, folding up like
miniature parasols when
there is little sun. Leaves appear atop upward-pointed petioles up to 2½" (6.3 cm) in length.
They are usually green, sometimes outlined in purplish, rarely dark reddish purple.
They are usually hairless.
Leaflets are obcordate (heart-shaped), with smooth edges. Individual leaflets are
¼-½" (6.3-12 mm) in size.
Flowers: Yellow, in groups of 2-7 on umbels. Each flower is
⁵/₁₆-¼" (8.3-6.3 mm) in diameter, with 5 yellow petals, 5 light green sepals, 10 stamens, and a pistil. Flowers appear from late spring to mid-fall.
Fruits: Seed capsules occur in groups of 3-5. They look like little
green bananas, bent slightly, ⅜-¾" (9.5-19 mm) long, and five-sided. Ripening capsules split
into five sections, exploding seeds up to several feet away. Seeds are just over ¹/₃₂" (1 mm) long
brown, oval, and flattened.
These are closely similar (see also this comparison):
9/7/2020 · Maquoit Bay Conservation Area, Brunswick, Maine
≈ 7 × 4½" (18 × 12 cm)
The furled leaves might be a reaction to heat or dryness. · 5/19/2016 · Bemis Road Trails, Pepperell, Massachusetts
≈ 9 × 7" (22 × 17 cm)
1/19/2021 · Nashua River Rail Trail, Groton, Massachusetts
7/17/2017 · Oak Hill, Littleton, Massachusetts
≈ 8 × 5" (20 × 13 cm)
1/19/2021 · Tom and Susan’s, Pepperell, Massachusetts