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Plant: Devil Thorn Weed (Tribulus zeyheri)

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Fri Mar 03, 2006 12:53 pm Unread post
A few things:
Devil thorn weed (Tribulus zeyheri)
Named after Carl Zeyher, 1799 - 1858, a German naturalist.

Range:

The arid and subarid regions of Cape Prov., Transvaal, Angola and SW. Africa.

Habitat:

On sandy soil, forming dense mats in overgrazed areas.

Description:

Perennial herb with spreading prostrate or somewhat ascending branches, finely hirsute with longer scattered bristle-like bulbous-based hairs on all vegetative parts; branches up to 1·2 m. long. Leaves unequal; the larger up to 9 cm. long, with up to 9 pairs of leaflets; the smaller up to 5 cm. long, with up to 4 pairs of leaflets. Leaflets 4–20 × 2–11 mm., oblique, very variable, oblong, oblong-ovate or ovate, acute or subacute, pubescent on both surfaces or glabrous above, often ciliate. Stipules up to 10 mm. long, linear-lanceolate to obliquely ovate, ciliate. Peduncle 1·5 to 2 times as long as the subtending leaf. Sepals 5–10 (12) × 1·8–2 mm., linear-lanceolate, acute, densely pubescent. Petals bright yellow, 10–20 (25) mm. long, up to 2·5 times the length of the sepals, broadly cuneate. Filaments 3–4 mm. long, anthers (1·2) 1·5–2·5 (3) mm. long. Style short; stigma 2–3 mm. long, slender, pyramidal. Ovary with stiff bristle-like tubercule-based hairs. Intrastaminal glands connate, forming a shallow cup at the base of the ovary. Fruit breaking up into 5 cocci, each usually with 4 (sometimes 6) equal spines, or spines reduced to thick warts, tuberculate on the dorsal crest and often laterally compressed.

Tribulus is a genus of plants found in many warm regions. The best-known member is Puncture Vine (T. terrestris), a widespread weed and also the source of a dietary supplement claimed to improve male sexual performance and help build muscle.

Tribulus species are perennial, but some grow as annuals in colder climates. The leaves are opposite and compound. The flowers are perfect (hermaphroditic) and insect-pollinated, with five-fold symmetry. The ovary is divided into locules that are in turn divided by "false septa" (the latter distinguish Tribulus from other members of its family).

Some species are cultivated as ornamental plants in warm regions. Some, notably T. cistoides, T. longipetalus, T. micrococcus, T. terrestris, and T. zeyheri, are considered weeds.

Danger to cattle
This plant is the cause of tribulosis or geeldikkop (literally, "yellow big-head") in sheep that have eaten the plant. Tribulosis is a photodermatitis (Steyn 1934, Watt and Breyer-Brandwijk 1962). The toxic principles of the plant cause liver damage and accumulation of phylloerythrin in the blood. Phylloerythrin, which is a breakdown product of chlorophyll, acts as a photosensitising agent. A suggestion of photodermatitis in man from the plant (Mathews 1937) lacks confirmation.

More photo's
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Junior Virtual Ranger
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Fri Mar 03, 2006 1:09 pm Unread post
... and a few more common names:
devil's thorn
dubbeltjie
duwweltjie
dubbeltjiedoring
platdubbeltjie
volstruisdoring



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Junior Virtual Ranger
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Fri Mar 03, 2006 6:16 pm Unread post
Jannie is this not the same plant that when you rub the leaves on your hands together with some water it actually lathers like soap?



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Fri Mar 03, 2006 6:33 pm Unread post
Penny wrote
Jannie is this not the same plant that when you rub the leaves on your hands together with some water it actually lathers like soap?


I think you are right, Penny, we learnt that at EcoTraining.


WANTED - Photo of Devil's Thorn in KTP

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Joined: Sat May 20, 2006 10:06 am
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Mon Mar 08, 2010 6:54 pm Unread post
Hi,
Does anyone have a photo of the Devil's thorn - Elandsdoring -Dicerocaryum eriocarpum - for publication in my revised guide "Kgalagadi Transfrontier Park"? Flower and pod if possible. Full acknowledgment and a copy of the book will be given.
Thanks
Peter


Re: WANTED - Photo of Devil's Thorn in KTP

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Junior Virtual Ranger
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Mon Mar 08, 2010 7:14 pm Unread post
Image
not good enough for a book, but here is the flower


Re: WANTED - Photo of Devil's Thorn in KTP

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Junior Virtual Ranger
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Mon Mar 08, 2010 7:18 pm Unread post
Image

plus a few more


Re: WANTED - Photo of Devil's Thorn in KTP

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Wed Mar 10, 2010 7:53 am Unread post
Hi,
Thanks. These are dubbeltjies not devil's thorns! I know .. I made the same mistake initially. Thanks for the interest and the effort. appreciate it.
Regards
Peter


Re: WANTED - Photo of Devil's Thorn in KTP

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Wed Mar 10, 2010 9:12 am Unread post
Hi forestgump,
I probably put my foot in it! The common names are the problem. Depending on the reference, Devil's thorn is either Dicerocaryum or Tribulus! Gunong means place of Devil's thorn. Which one do I choose? I would like to show readers what the flower looks like that gave this place its name.
I don't think this debate is over yet.
Regards
Peter
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