Description:

• Deciduous trees, small to medium-sized, with branches leafy at apex, with aromatic oils and cystoliths in leaves and stems; plants monoecious or polygamous
• Leaves alternate, simple, almost circular, entire or 3-5-lobate, with 3-5 major veins arising at or near base, whitish tomentose beneath, with long petioles; stipules 0
• Inflorescences dichasial, ebracteate, in axils of upper leaves
• Flowers bisexual or unisexual, mostly male, ± regular, epigynous, many, hairy, very small
• Perianth of 4-8 ± free tepals, equal or unequal, 2 larger than the rest and accrescent in bisexual flowers, linear or oblong-spatulate, in a single whorl, imbricate, obtuse
• Stamens usually 4 or 5, in a single whorl, much exserted, arising at base of perianth; filaments with dorsal appendages; anthers 2-thecous, broadly oblong, dehiscing laterally by 2 flap-like valves opening upwards
• Staminodes as many as and alternating with stamens, or more numerous, ± clavate, ± glandular, partly connate, or with a single peltate staminode opposite style
• Ovary inferior, 1-locular; ovule solitary, pendulous, anatropous, bitegmic and crassinucellar; style straight; stigma sessile, obliquely expanded
• Fruit a bony nut, ovoid, apically provided with 2 terminal large spatulate wings formed by accrescent perianth segments
• Seed broadly oblong, without endosperm; embryo straight
• x = 15 (1 report)

Classification Notes:

• Gyrocarpus Jacq. and Sparattanthelium Mart. sometimes separated as Gyrocarpaceae by e.g. Shutts (1960), but Kubitzki (1969, 1993) treats it as subfamily Gyrocarpoideae

Nomenclature:

• Gyrocarpus Jacq.
  • Jacquin: 282, t. 178, fig. 80 (1763)
  • Brown: 404 (1810)
  • Pax: 129 (1889)
  • Sprague: 189 (1909)
  • Schreiber: 1 (1968)
  • Kubitzki: 180 (1969)
  • Verdcourt: 6 (1985)
  • Thulin: 20 (1993)
  • Kubitzki: 337 (1993)
  • Stannard: 60 (1997)

Distribution & Notes:

• Global: Species 3 and 11 subspecies, widespread in tropical countries, 1 in Central America, 1 species with 2 varieties in NE and E Africa
• Southern Africa: Species 1: Gyrocarpus americanus Jacq. subsp. africanus Kubitzki, Namibia and Northern Province