Tribulus cistoides L.

Global description

Tribulus cistoides is a prostrate herb, hairy, with opposite and composed leaves. At each pair, there is a large leaf opposite a smaller one. The flowers are solitary at the base of the leaf. The 5 petals are yellow. The fruit forms a ball of 12 to 16 mm diameter, bristling with strong straight thorns. At maturity it is divided into 5 quarter with 2 strong spines on the top and 2 shorter downwards.
 
Cotyledons
 
Cotyledons are oblong, shortly stalked. The blade is 10 mm long and 2.5 mm wide. It is finely pubescent and marked with 3 longitudinal veins.
 
First leaves
 
First leaves are compound, opposite. A large leaf develops opposite a small leaf. The first leaves has 4 to 5 pairs of elliptical leaflets, asymmetrical at the base and finely pubescent.
 
General habit
 
Prostrate herb, extensively branched, growing in patches that may cover a large area, up to 2 m in diameter.
 
Underground system
 
Branched taproot.
 
Stem
 
Stem is cylindrical, solid, 30 to 100 cm long. The stems are covered with two types of hairs. Long and simple hairs are mixed with a short pubescence of variable density. The branches are alternate and are born in the axils of the shortest leaf of each pair.
 
Leaf
 
Leaves are opposite, compound, paripinnate. For each pair, a short leaf not exceeding 2.5 cm in length is located opposite a long leaf of 3 to 6.5 cm. There is a rotation at each node of the short and long leaves. The leaves are short-stalked. The stipules, linear or very narrowly oval, are 5 to 10 mm long, one shorter than the other. The leaflets by 6 or 8 pairs, are obliquely oblong or elliptic, 8 to 14 mm long and 3 to 4.5 mm wide. The base is asymmetrical and the apex is acute or obtuse, sometimes mucronate. The leaflets are sessile or very shortly stalked. The venation is inconspicuous. The leaflets bear, especially in the early stage, simple and applied hairs.
 
Inflorescence
 
Solitary flowers that grow at the axils of the smallest leaf.
 
Flower
 
Flowers held by a peduncle, 4 to 11 mm long, which expand at fruiting and reaches 12 to 18 mm. Their hairs are identical to that of the stem. The calyx consists of 5 persistent narrowly ovals sepals, 5 to 7 mm long and 1 mm wide and hairy on the back. The corolla consist of five free yellow petals, glabrous, delicate and fugitive, obovate shaped, 6 mm to 11 mm long and 2.5 to 6 mm wide, exceeding the sepals, forming an open flower of 2 to 3 cm of diameter. 10 stamens with a filament of 1.5 to 4 mm long. The ovary densely hairy is covered with silvery and robust hairs. The style is gradually transformed towards the top into a long stigmatic of 1 to 3 mm, cylindrical or narrowly pyramidal.
 
Fruit
 
Globular fruit with 5 angles, 12 to 16 mm in diameter (including spines), variously tuberculate and hairy, with strong straight spines. It consist of 4 to 5 mericarps in the shape of a quarter of an orange. Each mericarp has a convex outer surface variously tuberculate and hairy. It has 2 large straight radiating spines and sometimes some smaller spines. At maturity the mericarps separate and serve as a dissemination organ.

Origin

Tribulus cistoides is native to East Africa, Indian Ocean Islands, South East Asia, Australia and New Caledonia.

Worldwide distribution

Introduced in Central and Northern South America. It is considered an invasive species on the southern coasts of America, in Hawaii, Mauritius, Madagascar and in the Northern Territories of Australia.

https://www.gbif.org/species/5421117