Exploring Oxalis

Things are pretty quiet on the Corydalis and Dicentra front. There are a few leaves here and there, making the most of any fine autumn weather that passes through. The tuberous Corydalis are tucked away under a blanket of leaf mould; no doubt they are fidgeting around beneath their cover, sending roots into the freshly wetted soil and slowly preparing for spring. The pots of seed too, hopefully, will be taking advantage of the season’s dampness; finishing their maturation in the soil, waiting for the cold to bite, finally germinating with end of winter in sight. All of this happens without my help and for the most part away from my watchful eye. For now my attention turns to other things: Oxalis are the main contenders.

The Oxalis genus is broad and varied, but the I suppose so many genera are. By and large they form bulbs or fleshy storage roots, their leaves possess three leaflets (mostly) and their flowers have five petals. When we come to habitat and growing conditions, the wants and desires of Oxalis vary widely. There seems to be little information available to the grower, and what information there is can be diffuse and confusing (not a criticism of the authors of various articles – there just doesn’t appear to be much that cohesively and clearly brings things together). Here are a few things I’ve managed to glean from my limited time growing these plants thus far.

Giving Oxalis a Bad Name

I’d better add a few qualifiers here. There are a few members of the Oxalis genus which are distinctly weedy: Oxalis corniculata, Creeping Woodsorrel to it’s friends (and, indeed, it’s enemies), is a well known example of this. In fact I have a pretty sumptuous spread of this particular Oxalis growing in between the slabs on the patio. There are a few other candidates for categorisation as weeds; Oxalis debilis being one such character. Several species are perfectly capable of making a nuisance of themselves in the garden, although I’m sure this works to their advantage in their natural habitats.

South America

The continent of South America is home to a vast range of Oxalis, with the mountains of Argentina and Chile providing rich pickings for the alpine enthusiast. Oxalis enneaphylla is the only species I have from this area of the world, and one that has been a good grower for me:

Oxalis enneaphylla rosea
Oxalis enneaphylla ‘Rosea’ (picture taken Summer 2021)

There are a number of cultivars and hybrids of O. enneaphylla which look to be worth seeking out, along with O. adenophylla; a similar South American species. To reduce an entire continent’s stock of the genus to two species would be simplistic (for example: Oxalis tuberosum, otherwise known as Oca, is an important food source; O. triangularis is a popular houseplant), but as far as my gardening interests go, these two are where I’m beginning my explorations.

South Africa

Another part of the world with a plentiful array of Oxalis is South Africa. There seems to be an overwhelming number of species found here; apparently over 200. Only a small number of these can be bought and grown in the UK – probably for the best. Of particular interest, given the current season, is that a large number of them are autumn and winter growing (the majority of the South American species are summer growing/winter dormant). The undoubted star of the greenhouse as we speak is Oxalis massoniana:

Oxalis hirta ‘Gothenburg’ looks to have a similar habit but isn’t quite at the flowering stage yet:

Oxalis hirta gothenburg

Elsewhere, O. convexula and flava are starting into growth but don’t seem to be particularly thriving at the moment:

An Attempted Summary

Just as reducing South America to two species is a little absurd, summing up the Oxalis genus by reducing them to South American or South African is equally inappropriate. Case in point, Oxalis magnifica, hailing from Mexico:

Regardless, the human mind sees patterns and similarities wherever it focuses it’s attention; that’s how we make sense of the world and the things contained therein. It certainly isn’t necessary for us to be able to neatly group everything we interact with into easily manageable categories, yet having some understanding of the connections between plants can help to us to provide the conditions they need to thrive. Clearly it isn’t necessary for us to collect things either, but that particular facet of the human condition might need to be a topic for another day. For now I’m happy to collect and to categorise: learning little, mastering less, rolling about in my ignorance like a pig in muck.

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