Echinodorus

Scientific name

Echinodorus Rich. ex. Engelm.

Common names

Amazon sword plant, sword plant, burhead

Family

Alismataceae

Native distribution

America

Species commonly cultivated

Echinodorus amazonicus Rataj (Brazil)

E. angustifolius Rataj (Brazil)

E. aschersonianus Graebn. (Brazil to Argentina)

E. x barthii H. Mühlberg (artificial hybrid)

E. berteroi (Spreng.) Fassett (northern Central America, sporadic in South America)

E. bleheri Rataj (unknown)

E. bolivianus (Rusby) Holm-Niels. (South America)

E. cordifolius (L.) Griseb. (southern U.S. to Venezuela)

E. grandiflorus (Cham. & Schltdl.) Micheli (Mexico to Argentina, Cuba)

E. horizontalis Rataj (South America)

E. opacus Rataj (Brazil)

E. osiris Rataj (southern Brazil)

E. parviflorus Rataj (Peru, Bolivia)

E. quadricostatus Fassett (Central and South America)

E. tenellus (Martius) Buchenau (America)

E. uruguayensis Arechav. (South America)

(numerous additional species and hybrids traded)

Adventive distribution

some range extensions of American species into North America

Weed status

Echinodorus cordifolius is commonly a minor weed in rice fields.

Habit

amphibious, emergent rosette plant

Brief description

Annual or perennial. Stem rhizomatous or stoloniferous, compact. Leaves in a basal rosette, sessile or petiolate; leaf blade highly polymorphic in shape and size, linear to broadly ovate, venation palmate to parallel; base attenuate or cordate; margin entire. Inflorescence erect or creeping, with flowers in simple whorls or compound whorls with branches bearing flowers; creeping inflorescence developing bulbils (daughter plants) and rooting at nodes. Flowers bisexual, pedicellate, with 3 green sepals and 3 white petals; stamens 9 to numerous. Fruit consisting of numerous seeds, often in a burr shape. Dispersal by seeds or plantlets from inflorescence or stolon.

Natural habitat

lakes, rivers, swamps, and wet ground

Additional comments

Echinodorus is an extremely popular genus of plants in the aquarium hobby. There are 26-28 species (plus some subspecies) of Echinodorus in the New World, with many cultivated for aquaria or ponds. It is difficult to separate individual species of the genus, as they are remarkably homogeneous in their morphology. To further complicate species diagnoses, numerous artificial hybrids (e.g. 'Tropica Marble Queen', 'Apart', 'Oriental') are produced every year for the trade. A characteristic feature used to distinguish Echinodorus from other closely related genera is its bisexual flower, always of three petals and three sepals.