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Here's another of my Kalahari (October 1992) mystery plants. The flowers look like a kind of hibiscus, but the leaves look like thistle ... Can anyone help with ID?

Having consulted my dog-eared copy of Van Rooyen's "Flowering plants of the Kalahari dunes," I have come to the reluctant conclusion that the plant is Argemone ochroleuca, the Mexican poppy. This is an exotic and noxious weed (hence my reluctance!) which exudes a yellow latex when cut, and is noxious to humans and stock. It occurs in disturbed areas and dry river beds.

Of course, someone with better botanical knowledge may well prove me wrong, but that's my attempt.

(arks, if you want to borrow my plant book for your next trip, you're more than welcome to add some dog-ears! )

Thanks for the ID, restio, and the offer of your dog-earred field guide! I'm sorry to hear that this is an invader, but we can hope that it's been erradicated since 1992??

seen on my recent trip in October. Any help please.

Richard

Hi Richard,

This a the Yellow-flowered Mexican poppy (i've also heard the name Devil's fig), Argemone Mexicana L, Bloudissel, geelblom (Afrikaans).

Unfortunately it is a declared weed and listed as a category 1 plant…

Category 1 Plants
This is the strictest category and these are prohibited plants that will no longer be tolerated, neither in rural nor urban areas, except with the written permission of the executive officer or in an approved biocontrol reserve. These plants may no longer be planted or propagated, and all trade in their seeds, cuttings or other propagative material is prohibited. They may not be transported or be allowed to disperse.

Plant species were included in this list for one or more of the following reasons:
They might pose a serious health risk to humans or livestock; Cause serious financial losses to land users;
Invade undisturbed environments and transform or degrade natural plant communities;
Use more water than the plant communities they replace;
or be particularly difficult to control.
Most of the plants in this category produce copious numbers of seeds, are wind or bird dispersed or have highly efficient means of vegetative reproduction.

Whereas some of these plants were introduced inadvertently (have no obvious function to fulfil in South Africa and are generally regarded as undesirable) many of them are popular garden or landscaping plants. What they all have in common, however, is the fact that their harmfulness outweighs any useful properties they might have.

The Mexican poppies (Argemone ochroleuca and A. mexicana) are spiny, annual herbs that originate from Central America (Mexico) and are naturalised in most semi-tropical countries of the world. In South Africa. A. ochroleuca is the more abundant species of the two.
They are prolific seed producers with seed numbers ranging from 4000 to 30 000 (the spiny capsules split into five lobes and release numerous small black seeds).
Ecological impact / threat: Prolific in disturbed sites. Competes with agricultural crops and indigenous ruderal species. Contaminates crop seed. Spiny fruits and leaf tips can adhere to sheeps wool.
Its toxicity to animals and humans is a concern as they establishes readily on overgrazed pastures, wasteland, roadsides, abandoned lands, cultivated lands, riverbanks and riverbeds.
Argemone seeds are known to have caused human fatalities in the Western Cape Province as a result of wheat contamination, and its sap and leaves are also known to be irritants.

MEXICAN POPPIES TARGETED FOR BIOLOGICAL CONTROL

The ARC-PPRI (Agricultural Research Council - Plant Protection Research Institute) is currently investigating the use of biological control as a management tool. A recent trip to Mexico yielded two weevil species - one feeding on the flowers and the other on the fruits of Mexican poppy. The weevils are being cultured at their Rietondale (Pretoria) quarantine facility where host range trials and impact studies will be conducted.

Early Spring showed me lots of fascinating plants in the various parks I visited, so I'm hoping those more knowledgable than I can help me with IDs.

First, I saw these pretty yellow flowers in many area of the park. These pix are from (1) Shimuwini, (3) just north of the Letaba low level bridge (H14), and (2,4) along the S3, where one dry riverbed (5) was full of them. Are they all the same plant? Or similar?? Or ... ???

really a pity that you saw them in many areas of the park arks, as they are invasive weeds. Probably why you saw so many is because they unfortunately spread very easy as I explained to Richard Harris here

Your flowers are both Mexican Poppies - those with the yellow flowers are: Yellow-flowered Mexican poppy, Argemone Mexicana (L), Geelblom Bloudissel (Afrikaans).

And those with the white flowers... you've guessed it... White-flowered Mexican poppy, Argemone ochroleuca Sweet. subsp. ochroleuca (L), Witblom bloudissel (Afrikaans).

All the info i gave in that post applies to both these poppies

Heres another plant from Timbavati, we put it down as Mexican poppy (Argemone mexicana) but we're really not sure. Does that one grow in South africa? Can anyone id it?
/Neil
http://farm3.static.flickr.com/2088/218 ... cbc3_b.jpg

Niel, there's quite a bit of info on this poppy in the ID thread. There's a yellow one and a white one, and they are both alien invaders

Thanks Arks, Then we'll change our id to Argemone ochroleuca
, and it's pity we didn't stamp on it!
We've seen it before on Gran Canaria , together with Oxalis pes-caprae!
/Neil