Common Yellow Woodsorrel (Wildflowers of Eisenhower State Park)

Common Yellow Woodsorrel

Oxalis stricta

Summary ⁷

Oxalis stricta, called the common yellow woodsorrel (or simply yellow woodsorrel), common yellow oxalis, upright yellow-sorrel, lemon clover, or more ambiguously and informally "sourgrass" or "pickle plant", is a herbaceous plant native to North America, parts of Eurasia (including India), and has a rare introduction in Britain. It tends to grow in woodlands, meadows, and in disturbed areas as both a perennial and annual. Erect when y

Description ⁸

This perennial plant is typically 3-8" tall, although sometimes it becomes up to 1' tall. This plant often branches abundantly, particularly toward its base. The stems are light green and terete; they are covered with short appressed hairs. Alternate leaves occur along the stems; they are trifoliate. In the absence of sunlight, the leaflets of these trifoliate leaves droop downward and fold along their central veins; this process reverses itself when sunlight reappears. Individual leaflets are ¼-½" (6-13 mm.) long and similarly across; they are obcordate in shape and smooth (entire) along their margins. Both the upper and lower leaflet surfaces are pale green; the upper surface is glabrous or nearly so, while the lower surface is covered with short appressed hairs. The ascending petioles of the leaves are up to 2½" long, light green, and terete; they are covered with short appressed hairs. The petiole bases are slightly swollen as a result of their fused stipules. Small umbels of 2-6 flowers are produced from the axils of leaves. These flowers are about ¼" (6 mm.) or a little more across when they are fully open. Each flower consists of 5 yellow petals, 5 light green sepals, 10 stamens, and a pistil. The 5 styles of the pistil are joined together, except at their apices. The petals are oblanceolate in shape with either broadly rounded or slightly notched tips; sometimes they are reddish toward their bases. The sepals are oblong-lanceolate in shape, covered with short appressed hairs, and about 3-4 mm. in length; they are shorter than the petals. The pedicels are up to 1" (2.5 cm.) long, light green, and covered with short appressed hairs; they are initially ascending or erect while the flowers are in bloom, but they later become reflexed (bent downward) as the seed capsules develop. At the base of each umbel, there is a pair of tiny linear-lanceolate bractlets. The blooming period can occur from late spring to the mid-autumn; a small colony of plants may remain in bloom for 2-4 months. The flowers are diurnal. Afterwards, the flowers are replaced by seed capsules about 8-20 mm. long that are cylindrical in shape and 5-sided; their apices are beak-shaped. Immature capsules are light green and their sides are covered with either short appressed hairs or a combination of short appressed hairs and long spreading hairs. At this time, the pedicels become sharply reflexed, bending slightly to moderately downward at their bases, and then bending sharply upward near the bases of the seed capsules to hold them erect. As the capsules continue to mature, they split open into 5 parts to eject their seeds up to several feet away from the mother plants. The small seeds are about 1.0-1.5 mm. long, reddish brown to brown, broadly ellipsoid in shape, and somewhat flattened; they have several transverse ridges that are often whitened. The root system consists of a taproot that branches.

Sources and Credits

(c) Kelly Fuerstenberg, some rights reserved (CC BY-NC), uploaded by Kelly Fuerstenberg
(c) Miroslav Deml, some rights reserved (CC BY), https://www.biolib.cz/IMG/GAL/9211.jpg
Jan Ševčík, no known copyright restrictions (public domain), https://www.biolib.cz/IMG/GAL/99805.jpg
Ivo Antušek, no known copyright restrictions (public domain), https://www.biolib.cz/IMG/GAL/101423.jpg
Ivo Antušek, no known copyright restrictions (public domain), https://www.biolib.cz/IMG/GAL/101424.jpg
(c) anonymous, some rights reserved (CC BY-NC), http://www.biopix.com/PhotosMedium/JCS%20Oxalis%20stricta%2028748.jpg
(c) Wikipedia, some rights reserved (CC BY-SA), http://en.wikipedia.org/wiki/Oxalis_stricta
(c) John Hilty, some rights reserved (CC BY-NC), http://eol.org/data_objects/29447265

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