Family: Zygophyllaceae
Tribulus
Citation:
L., Sp. Pl. 386 (1753).
Derivation: Greco-Latin for the 4-pointed military instrument called the 'caltrop', employed to lame advancing cavalry, with 3 of the points always upturned; a name also applied to T. terrestris.
Synonymy: Not Applicable Common name: Caltrops.
Description:
Annual, biennial or perennial, usually prostrate herb, rarely erect shrub; leaves paripinnate, opposite (pairs unequal) or alternate.
Flowers solitary, pseudoaxillary, pedicellate; sepals and petals 5, imbricate, caducous; stamens 10 (rarely by abortion fewer), the outer opposite the petals; filaments filiform or subulate, without appendages; disk fleshy, annular, 10-lobed; nectariferous glands episepalous, 5 between the calyx and corolla and 5 between the inner stamens and ovary; ovary 5-lobed, 5-celled, with 2-5 ovules in each cell; style simple, cylindrical, 5-ridged, deciduous; stigma terminal, pyramidal or globose.
Fruit separating into 5 (sometimes reduced by abortion to 3 or 4) woody indehiscent usually spiny cocci, when winged the wings are in the position of the extended walls segregating the cells and split longitudinally, so that each coccus retains 2 (halves of) wings at its flanks; seeds without endosperm, separated by transverse or oblique septae which develop after fertilisation.
Distribution:
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About 25 species of the Old World of which 1 is introduced in North and South America; in Australia about 10 species; on sandy or stony ground, often on gravelly roadsides.
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Biology:
No text
Taxonomic notes:
Fully ripe fruits are needed for the recognition of the species. (El Hadidi (1978) Taeckholrnia 9:59-66.)
Key to Species:
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1. Fruit with 5 vertical wings; cocci with 1 pair of short conical prickles |
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T. macrocarpus 3. |
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1. Fruit without wings, with prickles, or muricate |
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2. Fruit strongly depressed, stellate, with 5 stout spreading spines,flat at the base, conical at the apex |
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T. astrocarpus 1. |
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2. Fruit not depressed, more or less globular, with 10 or more distinct prickles, rarely only muricate |
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3. Prickles of fruit few; each coccus with 2 divergent spines on their back above the middle and 2 shorter conical spines near the base directed downwards; flowers small, 6-15 mm across; sepals 3-5 mm long; petals 3-10 mm long |
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T. terrestris 5. |
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3. Prickles of fruit numerous, covering the back of each coccus, or rarely cocci only muricate |
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4. Flowers to 2.5 cm across; sepals 5-8 mm long; petals 10-13 mm long; fruit to 2 cm across; cocci covered on their back with short conical hairy prickles, usually only 2-3 (rarely to 8) mm long, sometimes merely muricate |
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T. occidentalis 4. |
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4. Flowers to 5 cm across; sepals 12-15 mm long; petals 25-30 mm long; fruit 3.5-4 cm across; cocci with long (to 15 mm) and short (c. 5 mm) spines on their back |
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T. hystrix 2. |
Author:
Not yet available
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