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Name derivation:

Comon name ‘water hyacinth’.


Eichornia Kunth 1842

Order Liliales;  Family Pontederiaceae

Perennial aquatic dicot.


Free-floating flowering plant with thick waxy leaves arranged in a rosette that can reach 90 cm above the water surface, and feather-like roots suspended in lakewater (not anchored in sediments).  the leaf petioles are inflated and provide buoyancy with a high proportion of air, often 700% (7 cm3g-1) or more by volume in the lacunae of the leaf mesophyll.  The leaves are kept rigid by both the inflated lacunae of the mesophyll, and the colligative turgor pressure of their cells (Sculthorpe  1967).

Dense populations of stomates, 120 mm-2 occur on both sides of the leaf blades;  stomates open daily at ~ 5 AM and close by 5 PM (Ibid.  1967).

The showy pink or purple flowers form a panicle tup to 15 cm long.

The fruit is a capsule that contains up to 450 seeds.


Similar genera:




Globally distributed, reported from at least 50 countries.  Native to tropical and sub-tropical S. America.  Some species (e.g. E. crassipes) are considered invasives.



Sculthorpe, C.D.  1967.  The Biology of Aquatic Vascular Plants.  Edward Arnold Publishers, London (610 pp).