Eichhornia azurea

Name and classification

Eichhornia azurea (Sw.) Kunth
Family Pontederiaceae

Common names

anchored water-hyacinth, rooted water-hyacinth

Disseminule

seed

Description

Fruit a capsule with numerous seeds. Seeds terete, oblong to narrowly oblong in outline, ca. 1.5–2.6 mm long, 0.3–0.9 mm wide and thick, with ca. 10 longitudinal ridges or membranous wings evenly spaced around seed. Testa light yellow-orange to yellow-brown; surface with glistening, fine horizontal striations in between ridges. Hilum terminal, often with persistent funiculus 0.4–0.6 mm long; chalazal end obtuse or depressed and often darker in color. Embryo axile-linear; endosperm readily visible.

Identification considerations

Seeds develop from an anatropous ovule, characteristic in the Pontederiaceae, resulting in both ends being distinctly featured. The chalazal end is opposite the hilar end.

Similar species

Eichhornia crassipes (Sw.) Kunth (non-FNW)

Heteranthera limosa (Sw.) Willd. (non-FNW)

Monochoria hastata (L.) Solms-Laub.

Monochoria vaginalis (Burm. f.) C. Presl.

Distribution

native to Mexico, Central America, and South America, also Jamaica; introduced to India, Iran, and the United States

Habitat

in mud along rivers, lakes, marshes, canals

General information

Eichhornia azurea is a perennial aquatic plant with submersed and emersed leaves, up to 100 cm tall. In the neotropics, with other aquatic plants, it forms floating masses that obstruct navigation. Propagation is by whole plants, stem fragments, fruits, and seeds. Eichhornia azurea was introduced into the U.S. as an aquatic ornamental but has not become established as a weed here.

seeds

seeds

seeds

seeds

A, seed; B, longitudinal section of seed showing embryo; C, transection of seed; drawing by Lynda E. Chandler

A, seed; B, longitudinal section of seed showing embryo; C, transection of seed; drawing by Lynda E. Chandler

chalazal end of seed

chalazal end of seed

hilar end of seed

hilar end of seed

seed, detail of surface

seed, detail of surface