Description:

• Herbs, subshrubs or shrubs; branches often jointed at nodes
• Leaves opposite or subopposite, rarely alternate or fascicled, often somewhat fleshy, simple, (1)2- or 3-foliolate or pinnate; leaflets sessile, opposite, usually oblique, entire; stipules persistent, leathery, hairy or spinescent
• Flowers bisexual, regular, solitary, 2-nate or occasionally in axillary cymes; bracts on peduncle 0
• Calyx with (4)5 sepals, free or connate at base, persistent or deciduous, imbricate
• Petals (4)5, rarely 0, free, imbricate or contorted
• Disc usually present
• Stamens as many or twice as many as petals, often unequal in length; filaments free, often with appendages at base; anthers 2-thecous, opening inwards with longitudinal slits
• Ovary on disc, superior, 4- or 5(10)-locular, furrowed, angled or winged, glabrous, bristly or villous, with 2-many pendulous ovules on axile placentas in each locule; style simple or ovary occasionally with 5 or more styles, longer than ovary to 0; stigma simple, rarely discoid
• Fruit a capsule, sometimes fleshy, often splitting into 5 indehiscent mericarps
• Seeds pendulous, usually with endosperm

Classification Notes:

• Hadidi (1977) places Tribulus L. in the family Tribulaceae

Nomenclature:

• Zygophyllaceae
  • Brown: 545 (1814) as Zygophylleae
  • Sonder: 351 (1860) as Zygophylleae
  • Oliver: 282 (1868) as Zygophylleae
  • Phillips: 432 (1951)
  • Launert: 125 (1963)
  • Scholz: 251 (1964)
  • Schreiber: 1 (1966)
  • Hadidi: 1 (1972)
  • Hadidi: 1 (1985)

Distribution & Notes:

• Global: Genera 27, species ± 250, fairly cosmopolitan in tropical and subtropical areas, mainly in hot, arid, occasionally also saline regions
• Southern Africa: Genera 8, species 55, mainly in the southern and western parts of the area

References:

• BROWN, R. 1814. In M. Flinders as Zygophylleae, A voyage to terra australis 2. G. & W. Nicol, London
• HADIDI, M.N. EL. 1972. Zygophyllaceae. Flora Iranica 98
• HADIDI, M.N. EL. 1977. Tribulaceae as a distinct family. Publications from the Cairo University Herbarium 7-8
• HADIDI, M.N. EL. 1985. Flora of tropical East Africa. Zygophyllaceae
• LAUNERT, E. 1963. Zygophyllaceae. Flora zambesica 2
• OLIVER, D. 1868. Zygophylleae. Flora of tropical Africa 1
• PHILLIPS, E.P. 1951. The genera of South African flowering plants. Memoirs of the Botanical Survey of South Africa No. 25
• SCHOLZ, H. 1964. Zygophyllaceae. In H. Melchior, A. Engler's Syllabus der Pflanzenfamilien, edn 12, 2. Bornträger, Berlin
• SCHREIBER, A. 1966. Zygophyllaceae. Prodromus einer Flora von Südwestafrika 65
• SONDER, W. 1860. Zygophylleae. Flora capensis 1

Resources:

• Key to Zygophyllaceae genera

• Zygophyllaceae genera: