Oxalis bowei and root morphology...

Ron Vanderhoff rvanderhoff@sbcglobal.net
Mon, 04 Jan 2010 22:18:20 PST

You are looking at the large contractile roots of Oxalis bowiei (spelling). Several Oxalis possess these roots, species both from the Americas and from Africa. While these species also have functioning, absorptive roots, these contractile roots can be quite odd looking. They are often confused for rhizomes. Others mistake them as storage organs for water or starches, which they are not (someone correct me if I am wrong about this), 

O, bowiei has some of the largest of these types of roots, but they often go unnoticed in a pot or in a garden, since they are seldom seen. These specialized structures are annual growths. New contractile roots are produced each year, then turn mushy and eventually rot and disintegrate. In a pot, while growing, they will often wind around the inside of the container. If they are thick, long and fleshy, like those of O bowiei, they can even push the plant up in the pot and over the lip during the growing season. Then, as dormancy ensues, the soil shrinks down again as the root finishes its purpose and dehydrates. During this sloughing off period, if the plant is unpotted and the soil/roots inspected, a slimy, decaying mass of gelatin-like contractile roots will be discovered. It can be quite alarming if you're not prepared - almost like giant white slugs have invaded the root system.

Ron Vanderhoff
California - where the weather is mild and South African Oxalis are now blooming abundantly!

From: Chad Schroter <Chad.Schroter@sandisk.com>
To: Pacific Bulb Society <pbs@lists.ibiblio.org>
Sent: Mon, January 4, 2010 1:59:47 PM
Subject: [pbs] Oxalis bowei and root morphology...

I unpotted a small Oxalis boweii from a shared large deep 20" pot the other day and in addition to the "normal" large bulbs at the surface there were several very large root growths circling the bottom of the pot (and also some purple tubers of ipomoea..) the connection to the surface was barely noticeable if any. Each growth (some in pairs) is smooth translucent white, nearly 12" long and about 1" in diameter at the widest point tapering to a point on each end. On one end of each were some flat wrinkly structures somewhat leaf like in appearance.

I have seen similar if much smaller root expansion on my 'beloved' O. pes caprae, but those are always strongly connected to the main stem, and don't have any "leafy" growths...

Do these things have a name ? They are somewhat scary looking...

Chad Schroter
Los Gatos, CA zone 9

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