Oxalis

Oxalis triangularis Photo: Annie’s Annuals & Perennials

To some, the mere mention of Oxalis makes their blood boil. Looking past the common, weedy types, we find a remarkable genus of some 800 known species. By far the largest member of the wood sorrel family (Oxalidaceae), members of this genus are remarkably widespread, found in virtually every part of the world outside of the polar regions. The diversity is especially astonishing in tropical Mexico, Brazil, and South Africa.

The leaves of many Oxalis species are reminiscent of clover, and in those species that contain three obovate and top-notched leaflets (arranged palmately) it’s easy to see a resemblance. One of the more curious characteristics of certain shade-loving Oxalis species (as with the burgundy O. triangularis) is their tendency to alter their leaf angle in response to light intensity. This response, which can even cause leaves to close to overcome photoinhibition, which is a decrease in the efficiency of photosynthesis when plants are exposed to an overabundance of light.

[caption id="attachment_16084" align="alignnone" width="660"...