Wild Oxalis from North America?

[Stephenb]

I got this one as a wild North American species. It has distinctive contrasting purple undersides to the leaves. Can anyone give it a name?

[Paddy Tobin]

Stephen,

Perhaps, Oxalis illinoensis which is a wild wood sorrel. Bit of a weed in the garden, certainly given favourable conditions it spreads with vigour.

Paddy

[Rodger Whitlock]

I was going to say it looks like the white flowered form of Oxalis oregana, "the redwood sorrel," but in fact it doesn't. That plant has quite pale green leaves. The pink-flowered form of Oxalis oregana does, however, have leaves much like those in your specimen.

Whatever it is, be very cautious about where you plant it. I started off with a small 4"/10 cm pot of the white Oxalis oregana and 10 years or so later it had filled an area roughly 8' in diameter. I dug up most of it summer 2007 (by hand using an ancient fern trowel), but this last summer some scraps of rhizome I'd missed sent up leaves. I anticipate I'll have to be alert for regrowth for several more years.

[Afloden]

Hello,
 
 I can say that it is definitely not Oxalis illinoensis or grandis, the more common of the two species. Both these are large woodland plants with stems to nearly 60cm tall topped with lots of large soft yellow flowers. Both can spread by rhizomes, but neither are very weedy.

 See here; http://tenn.bio.utk.edu/vascular/database/vascular-database.asp?CategoryID=Dicots&FamilyID=Oxalidaceae&GenusID=Oxalis&SpeciesID=illinoensis

 There are pictures of both species here.

 In my opinion that does look a lot like some O.oregona I have seen. You might look through CalFlora on the web. The selection of species, mostly western natives, and photos listed is very extensive.

 Aaron Floden
 Knoxville, TN
 UT Herbarium