Amphicarpic Paspalum Grass (Paspalum amphicarpum)
The Amphicarpic Paspalum Grass was described in 1942, it appears to be endemic to the western regions of Cuba: the type was collected in 1923 at the edge of a pool near Laguna de Piedras in the Province of Pinar del Río [it might actually also occur in South America, I wasn’t able to find out yet].
This is a glabrous, widely creeping aquatic or subaquatic perennial with ascending branches, it is furthermore known to produce subterranean spikes with cleistogame (self-pollinating) flowers as well as normal aerial inflorescences. [1][2]
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The species’ name appears in lists of extinct species, so is extinct at least on the island of Cuba to which it might have been endemic.
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References:
[1] Agnes Chase: The North American species of Paspalum. Contributions from the United States National Herbarium 28(1): 1-317. 1942
[2] H. E. Connor: Breeding systems in the grasses: a survey. New Zealand Journal of Botany 17: 547-574. 1979
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edited: 19.06.2020