Description :

• Annual or rarely perennial herbs; stems terete or quadrangular, glabrous
• Leaves opposite-decussate or verticillate, rarely alternate, ± sessile
• Flowers homomorphic or dimorphic, occasionally cleistogamous, small, usually solitary and subsessile in leaf axils, occasionally aggregated into terminal racemes or spikes, very rarely in axillary umbels; bracts foliose or scale-like, bracteoles 2, rarely absent
• Calyx : tube (3)4-6-lobed; lobes often alternating with cornate appendages; nectaries often present at base of tube
• Petals as many as calyx lobes or 0, sometimes unequal, entire, erose or pinnately divided
• Stamens 1-6, opposite sepals, arising at various heights in calyx tube, occasionally basal and appearing free, sometimes replaced by staminodes
• Ovary sessile or shortly stipitate, incompletely 2-4-locular, dissepiments interrupted above placentas; ovules small and many; style very short to long; stigma capitate or rarely bilobed
• Capsule septicidally 2-4-valved
• Seeds small, few or many, concave-convex, with evaginating mucilaginous hairs
• x = 8 (aneuploids, polyploidy)

Nomenclature:

• Rotala L.
  • Linnaeus: 143 (1771)
  • Fernandes: 312 (1978)
  • Cook: 9 (1979)
  • Immelman: 35 (1991)

Distribution & Notes:

• Global : Species ± 40, widespread in warm regions
• Southern Africa : Species 8, Namibia to KwaZulu-Natal