Heteranthera, Ruiz & Pavon, 1794

Carnevali, Germán, Stefano, Rodrigo Duno De, Ramírez-Morillo, Ivón M., Grande Allende, José R., Barrios, Yeni & Tapia-Muñoz, José Luis, 2022, Heteranthera yucatana (Pontederiaceae), a new, threatened species from the Mexican Yucatan Peninsula, Phytotaxa 547 (1), pp. 20-30 : 27

Key to Heteranthera in the Mexican Yucatan Peninsula

1. Leaf-blade clearly differentiated from petiole, variously ovate, elliptical to orbicular; the pseudo-petiole longer than the blade; flowers always purple or purple-violet............................................................................................................... Heteranthera limosa

- Leaf-blade not differentiated from petiole, linear; flowers purple-violet, lilac or yellow..................................................................2

2. Inflorescence sessile, axillary, with a solitary flower; flowers yellow, actinomorphic; all three anthers of the same size and shape. ............................................................................................................................................................................. Heteranthera dubia

- Inflorescence pedunculate, terminal, generally with several flowers, rarely only a single one; flowers lilac, zygomorphic; anthers of different sizes and shapes........................................................................................................................... Heteranthera yucatana