Oxalis stricta (Yellow Wood Sorrel)

Plant Info
Also known as: Common Yellow Oxalis
Genus:Oxalis
Family:Oxalidaceae (Wood Sorrel)
Life cycle:perennial
Origin:native
Habitat:part shade, shade, sun; fields, woods, lawns, disturbed sites
Bloom season:June - October
Plant height:6 to 20 inches
Wetland Indicator Status:GP: FACU MW: FACU NCNE: FACU
MN county distribution (click map to enlarge):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

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Detailed Information

Flower: Flower shape: 5-petals

[photo of flowers] Branched cluster of 2 to 7 blossoms on a long slender stalk up to 3 inches long emerging from the upper leaf axils. Flowers are yellow, 3/8 to ½ inch across, with 5 oblong, rounded petals and 5 lance-elliptic sepals about ¾ the length of the petals. The sepals can be smooth or variously covered in spreading hairs. Flower stalks are ½ inch or less in length, can be mostly smooth, or with a few scattered hairs pressed close to the stalk (appressed), or densely hairy with spreading hairs.

Leaves and stems: Leaf attachment: alternate Leaf attachment: whorl Leaf type: compound Leaf type: palmate

[photo of leaves] Leaves are alternate or in whorls with long slender stalks, palmately compound in threes, ½ to 1¼ inch across, usually green but sometimes dark reddish purple. The heart-shaped leaflets look clover-like and fold up at night and on cloudy days. Leaflets are toothless, surfaces are smooth except for scattered appressed hairs on the lower mid vein and along the leaflet edges.

[photo of stem hairs] Stems, branches and leaf stalks are variously hairy, from mostly smooth to densely covered with fine, spreading glass-like hairs as well as scattered, shorter, appressed and opaque hairs, but becoming less hairy with age. Many of the spreading hairs are sectioned, divided by lateral membranes (septate). Multiple stems from the base are erect to spreading and much branched in the upper plant. Branches of spreading stems often grow more prostrate giving the appearance of a creeping stem but they do not root along the nodes.

Fruit: Fruit type: capsule/pod

[photo of fruit] The fruit is a green, erect, banana shaped capsule 3/8 to ¾ inch long, with 5 angled sides and the 5 sepals spreading at the base. A typical plant will have 3 to 5 capsules in a cluster, on erect to ascending stalks. Like the stem it has varying amounts of spreading, glass-like, septate hairs and a few scattered, shorter appressed hairs. The capsule stays green when ripe and the seeds are forcefully ejected when the capsule splits open.

[photo of seed] The seeds are just over 1 millimeter long, uniformly brown, oval, flattened on two sides with transverse ridges across the surface.

Notes:

Largely considered a weedy native, this and Southern Wood Sorrel (Oxalis dillenii) can be difficult to discern without a hand lens, or better yet a microscope using mature specimens. The characteristics to look for in Oxalis stricta are: the spreading glass-like hairs, the branching clusters with up to 7 flower buds and fruiting with up to 5 erect capsules on mostly upright stalks. The ridges on the seed are brown like the rest of the seed. O. dillenii typically has all appressed hairs, only 2 flowers in a cluster, 2 capsules on bent stalks, and white ridges on the seeds. Another very similar species is O. corniculata, a non-native that is low-growing and creeping, rooting at most nodes, with all brown seeds. O. corniculata has not yet been recorded in Minnesota but is present in neighboring states. Also as an observation, O stricta is more likely to be found along lawn and garden margins where they do not get frequent mowing and are often in part to full shade. O. dillenii is the predominant species in mowed areas in full sun and branches profusely from the base due to repeated cuttings.

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More photos

Photos courtesy Peter M. Dziuk taken in Ramsey County.

Comments

Have you seen this plant in Minnesota, or have any other comments about it?

Posted by: Gary - Maple Grove
on: 2013-07-09 15:30:09

Found this plant,I think, in my yard. I read somewhere this is only common as violet in norther Minnesota.

Posted by: Mike and Diane - Hermantown
on: 2013-07-29 13:19:10

We are sure we have this plant growing in our flower gardens near the house. It seems to come up everywhere we have a bird feeder. First in the front of the house and then on the side only after we relocated our bird feeder that contains wild bird mix bought at our local feed supply store. The plants are in clumps and have yellow flowers and there are a lot of them. Once we removed the bird feeder permanently they are not recurring.

Posted by: John - Todd County
on: 2015-10-19 10:59:01

This has grown all summer in the flower bed near my house. I let it grow after I saw the flowers come out, and thought it was a nice touch. I noticed that it grows in the flower bed near the bird feeder, but not so much in the one away from the bird feeder. Interesting.

Posted by: Bob - Camp Ajawah, Anoka County
on: 2016-06-20 08:43:19

We have both purple-leaved and green-leaved.

Posted by: Jane - Dakota County
on: 2016-07-21 11:27:30

This green-leaved sorrel is constantly overtaking my raingarden, lawn, flower beds, and woodland edge. It tries to compete with everything—lupine, harebells, hosta, aster, butterflyweed, etc. The lawn gets mowed once a week but the sorrel just grows as it pleases wherever it wants. I took a class in edible plants at the Dodge Nature Center several years ago and the green capsules are edible—you can add them to salads. The good news is that the capsules are really tasty and tangy!

Posted by: Craig L - Longville
on: 2017-06-18 14:34:23

Lots of it growing in my garden beds. I've always pulled them out before, but after rummaging around online, I've decided to let them go and see what happens. My mom called it "sweet clover" which is a bit of a misnomer as the leaves are actually rather tart - but fun to eat!

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