Oxalis--TOW
Mary Sue Ittner (Wed, 12 Nov 2003 22:51:05 PST)

Dear All,

I am enjoying all the participation in the topic of the week and appreciate
Robin's moderating as well. One of the things that frustrates me about this
genus is all the host of names that people mention. I always want to know
where that plant comes from, what kind of soils is it found in, when does
it get rainfall in nature, and when does it bloom.

I remembered that earlier on the Oxalis group that David Victor told about
a checklist to solve that problem.
"The author is Richard Clifton, who is the Editor for the
Geraniaceae Group. The checklist was produced three years ago and was
based on a review of the Index Kewensis, Salter's monograph of South
African Oxalis and various flora. It covers the naming of virtually all
species of Oxalis and their authorities and limited descriptive
material. There is also a wide critique of O. corniculata.

The checklist can be obtained from Richard's home address which is 7
Crabble Road, Dover, Kent, England, CT17 0QD. He is not on e-mail.

The checklist cost 15 UK pounds. Post and packing is in addition and will
cost two pounds for surface mail and more for air mail. Richard cannot
accept credit cards. Cheques are a problem because of exchange costs,
unless purchased locally and drawn on a correspondent UK bank. Probably
cash is best. "

Andrew Broome found this resource as a way to obtain it:
http://nhbs.com/xbscripts/bkfsrch/…

Does this checklist tell where each of the species is from or time of
bloom? I've looked at the Kew list before when I have been puzzled about a
name and often all that was listed was the name of the plant and the
authority and I am afraid I wanted more information than that.

For instance I was curious about the origin of the plant that Lauw and Uli
were talking about. It isn't in any of my references but I found in one of
my saved references that Oxalis crassipes was a plant from Argentina that
had become popular in the Gulf south of the USA where it bloomed in spring
and sometimes again in fall.

One thing that strikes me is that a lot of people are not growing Oxalis in
the mix you usually hear associated with it. I looked up what I could find
from Micael Vassar and found this:

"The potting mix for Oxalis depends on what kind of Oxalis you are
planting. I find that the winter growing species from the Western Cape area
of South Africa (now correctly the Southern Cape I think) all do best
planted in a very poor mix with little or no organic material. In
habitat they almost all grow in pure decomposed sandstone. For these winter
growing species I use 50% agricultural pumice, 40% washed builder's sand
and 10% leaf mould (or less). A mix of pumice and washed builder's sand
would be adequate without any organics at all. I fertilize with a 15-30-15
fertilizer at 1/4 strength about once a month. I don't like perlite because
of the dust and because it floats to the top in a planting mix.

The summer growing African species need a richer mix and can have up to 25%
organic material. They tend to have a longer growing season (some are even
evergreen).

Oxalis species from Central America and Mexico (mostly rhizomatous) are
mostly evergreen and also do best in a richer planting mix.

I plant all bulbs one inch (2.5cm) deep. Bulbs adjust themselves in the
planting mix to the correct depth. It is impossible to distinguish the top
from the bottom of some Oxalis bulbs so plant them sideways-always works well.

I find that Oxalis grow, flower, and produce replacement bulbs better if
grown on the hard side."
As I read on I found the following note from Will Ashburner:
"I do the opposite to Mike with regards planting mix. Mine is totally
organic (shredded composted pine bark and coco peat)with an air fill
porosity of 20% and full range of nutrients.

They multiply like rabbits and flower etc. I have never seen them in the
wild so they may be out of character and too lush, but ignorance is bliss."

It sounds like Oxalis are very flexible.

Mary Sue

Mary Sue Ittner
California's North Coast
Wet mild winters with occasional frost
Dry mild summers