New weed in California – African spiderflower (Cleome gynandra) - UC Weed Science

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Weed control, management, ecology, and minutia

New weed in California – African spiderflower (Cleome gynandra)

Author: Guy B Kyser
Author: Mohsen Mesgaran

Published on: July 20, 2018

Dr. Mohsen Mesgaran, who joined the Weed Science Group this year as our weed ecophysiologist, found this plant growing on the research farm at UC Davis.

African spiderflower on fallow ground at the research farm

Palmate compound leaves

Slim seedpods with tiny seeds

African spiderflower is a summer annual broadleaf plant in the caper family (Cleomaceae), growing up to 3 ft tall and wide. The flowers are white, somewhat tubular, with long red-to-orange stamens (see photos below). Interestingly, African spiderflower plants have three types of flowers - male, female, and hermaphroditic.

We have no idea how this plant got here. It is native to Africa, where the leaves are used as a vegetable; it is now widespread and invasive in many tropical to subtropical parts of the world. The USDA lists it as introduced in much of the United States southeast, from Texas to Virginia. Ellen Dean of the UC Davis Herbarium confirmed that the plant has not been reported in California before.

Mohsen and I pulled all the plants we found (a couple dozen or so), showed them to research farm personnel, and put the plants in the Plant Materials Bad Stuff dumpster for sterilization.

All photos are by Dr. Mesgaran.

Nice-looking, diffuse flowering heads which give the plant its common name

A single floret showing elongated stamens and pistil

Tags: agricultural weed (7), invasive (21), invasive weeds (90)

Comments: 3

Comments:

by Rebecca Ozeran

on July 24, 2018 at 3:23 PM

In a different blog this plant was mentioned as a crop in small community gardens/urban farms (fifth paragraph from the bottom: http://ucanr.edu/?blogpost=27139&blogasset=99473). Perhaps it is spreading from nearby cultivation.

Reply by Guy B Kyser

on July 24, 2018 at 3:31 PM

Thanks for the link - I hadn't seen that post. No doubt this can be a useful plant if it's growing where it's supposed to. But from a weed perspective, it makes me nervous when a plant appears from nowhere and spreads so quickly...

by James Bailey

on September 19, 2019 at 10:43 AM

If this plant is new for California, which it may well be, please retain a herbarium sample so Jepson can add it to the state list.