common or yellow wood sorrel
Oxalis stricta
Oxalidaceae

violet wood sorrel
Oxalis violacea
Oxalidaceae

The yellow-flowering species is derided by some [hi, Linda!] as a real nuisance plant. It is pretty, though. Is it a weed? Not when I find it in a natural setting like the Potomac gorge, where it doesn’t seem to grow in large swaths like it does in the garden. Yellow wood-sorrel is found all over the US except Oregon, California, Nevada, and Utah, and is listed as a weed by some authorities. It seems to have a long bloom period in the wild.

Violet wood-sorrel is found in all US states except Montana, Idaho, Washington, California, Nevada, and Utah. The plants hug the ground, but the flowers stand a few inches taller than the yellow species, and it doesn’t bloom as long. I’ve seen it in the gorge forming carpets as large as half a square meter. Before blooming, the leaves often have a violet tinge, especially on the edges, but it always seems to be gone by bloom time. A large patch never seems to produce more than a few flowers, but then this is only the third year I’ve observed it.

I feel it’s time to re-post this.
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