Acceptable Oxalis

Christiaan van Schalkwyk
Thu, 30 Apr 2009 01:12:17 PDT
Hi all

These are comments from various posts on this topic:

> I am curious what you mean when you say the bulbs renew each season.
> Most or all of the SA bulbous spp. I grow (several dozen) build up
> thick multi-season tunics around their bulbs, which seems to suggest a
> 'sedentary' organ that functions like a normal bulb.
> What is radically different, though, is how the new shoots, somewhere
> between the top of the bulb and the soil surface, produce that
> season's root system anew. The bulb itself also has roots (from the
> base) but these may be secondary?
Even most of these multi season thick bulbs form new bulblets inside the 
tunics of the older structures. Many produce the new bulb lower than the 
previous one (see eg. O haedulipes at…), 
and some even produce specialized contractile roots that actually pull the 
bulbs deeper (see…). 
Other simply grow roots/rhizomes/runners, from either the top of the bulb, 
the bottom of the bulb, or somewhere along the lenth of the stem, and form 
bulblets along the way.
But this is a long and difficult subject, maybe I should write a wiki page 
with illustrations on the roots and bulbs of Oxalis ? (Please - not this 
week !). I think that one of the reasons why Oxalis bulbs rather quickly and 
effectively change hemispheres are due to this renewal of the bulbs.

> Do any other dicots have what could be called bulbs?
Thanks Jim for a beautiful answer !

>So for me to think about selecting anything to grow here in the
>Chicago means that I'd need a list of desirable plants at Sutherland and
>then I'd check to see which of those withstood our winters here.   I'm sure
>that most folks in the PBS can get away with growing almost anything from
>South Africa. (No,  I know it's not really true.)  Might such a list be
>handy to you , say-- in the form of plants available from a local nursery

Dear Adam (and all other interrested parties)
Sigh and sad face :(
For most of it, we as South African do not appreciate the beauty, diversity 
and potential of our Flora, (and on my side I do not understand "cold" that 
well - a real "freezing" night means that the temperature dropped to -2 
Celsius !). Very few indigenous species are available in horticultural 
trade. For example, I've seen only five (!) species of Oxalis on sale at 
nurseries, and NONE of these are South African. Specialized nurseries might 
offer some SA species, Kirtsenbosch botanical gardens had about four (two 
colour forms of O glabra, two colour forms of O purpurea) the last time I 
was there, Cape seed and bulbs offer 27 (of which 3 are not SA) species, and 
some other nurseries offer a few. There are more South African Oxalis 
species available in trade overseas than in South Africa - see for example 
the lists of Dylon Hannon and Diana Chapman. There are also some exellent 
collectors, eg. Bill Baird, and Ron Vanderhoff. Some collectors out there 
(many on this list) are more passionate about our heritage than what we are.
It would seem that Jim's ramblings are contagious.
Some of the Michael Vasser collections from around Sutherland  might be 
worth trying to get hold of (obtusa: MV2285, 2291, luteola 4960, meisneri? 
4962, and Sp? 4729, 4767)

>That's why many alpines
>are grown under cover even though "perfectly hardy." It's not the
>cold, it's the humidity....
Luckily many SA Oxalis are used to winter rainfall !, and snow in the Little 
Karoo . . .

>In addition to the little Oxalis species of temperate South America,
>there is at least one really big one, O. gigantea, which is a shrub
>and I imagine there are similar manifestations in southern Africa.
No, sorry, all of the SA species have bulbs, only a few species can be 
regarded as large, but they regrow yearly from the bulbs, eg. O comosa, 
which can grow to a meter high.

I forgot about the crown bulbs ! They are quite horrid in numbers, I have 
counted up too 600 bulblets on a single plant of O. inaequalis. But I must 
admit that my efforts too grow these into mature plants have not been 
succesfull. O. inaequalis' bulblets at least stays in the pot when watered, 
O pocockiae have light winged crown bulbs than can be blown around, and are 
lifted up by the water


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