What's going on here (Oxalis)

Mary Sue Ittner msittner@mcn.org
Wed, 29 Mar 2017 07:18:31 PDT
A number of years ago Alberto Castillo donated to the BX what he called 
a double flowered form of Oxalis compressa. I expect that is where Jim 
got it. You can see photos here:


The leaves look a lot like Oxalis pes-caprae and the bulbs of this 
double form are a little different from the single form as my photos 
show. I found it was a lot less likely to flower than O. pes-caprae and 
worried about it so got rid of it, but there was some that got loose in 
one of the pots in my raised bed that I haven't unpotted. No flowers 
this year however, but the single form has been a blaze of bright yellow 
flowers for months. When the double form flowers, it flowers much 
earlier than Oxalis pes-caprae. There are supposed to be double forms of 
O. pes-caprae. Gastil and Nhu took some photos for the wiki that show 
the bulbs and the contractile roots and show how it can rapidly increase.


Cape Plants describes O. compressa as like O. pes-caprae, but petioles 
flattened and peduncles 3-6 flowered versus 3 to 20 in O. pes-caprae. 
And  Christiaan van Schalkwyk added this distinction to the wiki:

Oxalis compressa can be identified by the flattened or compressed leaf 
stalks. Oxalis pes-caprae has a brown bulb, without conspicuous 
longitudinal grooves. It may or may not have a stem. The bulbs I 
photographed of the double form of O. compressa had the grooves.

Fremontia, the journal of the California Native Plant Society has a 
double issue I recently received devoted to California Geophytes. I've 
really been enjoying reading all the articles. If I find time I may 
write about it in another post. I can't remember which article it was 
in, but one of them minimized the problem of O. pes-caprae except in 
disturbed places. But it is in state parks on the bluffs and spreading 
to other places in Northern California.  It appears in a new places I 
guess as Kipp says because the birds spread the bulbs. The leaves when 
young look a lot like clover and so when it first appears without 
flowers it isn't noticeable. Then a year or two later when you see the 
flowers you find out you are in trouble. It is flowering in abundance at 
the moment in this wet year.

Mary Sue

On 3/28/2017 9:14 PM, Kipp McMichael wrote:
> I assume this is Oxalis pes-caprae (which has been corrupted to "compress"?)

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