sentences:  Tristylous populations are however limited to the native lowland South America range of water hyacinth; in the introduced range, the M-morph prevails, with the L-morph occurring occasionallyand the S-morph is absent altogether.This geographical distribution of the floral morphs indicates that founder events have played a prominent role in the species' worldwide spread.Its habitat ranges from tropical desert to subtropical or warm temperate desert to rainforest zones.