Echinodorus

Scientific name

Echinodorus Rich.

Common names

Amazon sword plant, sword plant, bur headhead:
(n) inflorescence consisting of small closely packed stalkless flowers or florets arising at the same level on a flattened axis; of several types, including: discoid (composed entirely of disk flowers) and radiate (composed of central disk flowers and marginal ray flowers)

Family

Alismataceae

Similar genera

Alisma, Aponogeton, Butomus, Damasonium, Jasarum, Lilaeopsis, Ottelia, Potamogeton, Sagittaria

Native distribution

America

Species cultivated

(numerous additional species and hybrids traded)

Echinodorus amazonicus Rataj [synonym of E. grisebachii Small]

E. angustifolius Rataj [synonym of Helanthium bolivianum (Rusby) Lehtonen & Myllys]

E. x barthii H. Mühlberg (artificial hybridhybrid:
(n) a specimen produced by the sexual reproduction of two plants of different species or subspecies
)

E. berteroi (Spreng.) Fassett

E. bleherae Rataj [synonym of E. grisebachii Small]

E. bolivianus (Rusby) Holm-Niels. [synonym of Helanthium bolivianum (Rusby) Lehtonen & Myllys]

E. cordifolius (L.) Griseb.

E. gracilis Rataj [synonym of E. grisebachii Small]

E. grandiflorus (Cham. & Schltdl.) Micheli

E. horizontalis Rataj

E. latifolius (Seub.) Rataj [synonym of Helanthium tenellum (Mart. ex Schult.f.) J.G.Sm.]

E. magdalensis Fassett [synonym of Helanthium bolivianum (Rusby) Lehtonen & Myllys]

E. martii Micheli [synonym of E. subalatus (Mart. ex Schult.f.) Griseb.]

E. parviflorus Rataj [synonym of E. grisebachii Small]

E. quadricostatus Fassett [synonym of Helanthium bolivianum (Rusby) Lehtonen & Myllys]

E. tenellus (Mart. ex Schult.f.) Buchenau [synonym of Helanthium tenellum (Mart. ex Schult.f.) J.G.Sm.]

E. uruguayensis Arechav. [also offered under the synonyms E. aschersonianus Graebn; E. opacus Rataj; E. osiris Rataj]

Adventive distribution

some range extensions of American species into North America

Weed status

Echinodorus cordifolius is commonly a minor weed in rice fields.

Habit

amphibiousamphibious:
(adj) of a plant able to live on land or in water
, emergentemergent:
(adj) (syn. emersed) with parts raised out of the water; extending up out of the water
rosetterosette:
(n) a radiating cluster of leaves, usually close to the ground at the base of a plant
plant

Brief description

Annual or perennialperennial:
(adj) (of a plant) having a life cycle of more than two years
. Stem rhizomatousrhizomatous:
(adj) possessing rhizomes
or stoloniferous, compact. Leaves in a basalbasal:
(adj) at or pertaining to the base, or point of attachment
rosetterosette:
(n) a radiating cluster of leaves, usually close to the ground at the base of a plant
, sessilesessile:
(adj) attached directly, without a stalk
or petiolatepetiolate:
(adj) relating to or in the form of a petiole; bearing petioles
; leaf bladeblade:
(n) (syn. lamina) the flat, expanded part of a leaf, frond, or petal (excluding, e.g., the petiole)
highly polymorphicpolymorphic:
(adj) displaying multiple forms (of, e.g., an organ) in one organism
in shape and size, linear to broadly ovateovate:
(adj) egg-shaped in outline; generally with the broad end at or near the base
, venationvenation:
(n) the arrangement of veins in a leaf
palmate to parallel; base attenuateattenuate:
(adj) narrowing gradually to a point
or cordatecordate:
(adj) heart-shaped; in the form of two rounded lobes
; marginmargin:
(n) edge; rim
entire. Inflorescenceinflorescence:
(n) the arrangement of flowers on the floral axis
erect or creeping, with flowers in simple whorls or compoundcompound:
(adj) with two or more like parts, as in a compound leaf; divided into two or more subsidiary parts or orders, as in a compound inflorescence
whorls with branches bearing flowers; creeping inflorescenceinflorescence:
(n) the arrangement of flowers on the floral axis
developing bulbils (daughter plants) and rooting at nodes. Flowers bisexualbisexual:
(adj) having both male and female sexual reproductive structures on one individual or in one flower
, pedicellatepedicellate:
(adj) borne on a pedicel
, 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 inflorescenceinflorescence:
(n) the arrangement of flowers on the floral axis
or stolonstolon:
(n) an above-ground stem growing more or less horizontally and often forming adventitious roots at the nodes
.

Natural habitat

lakes, rivers, swamps, and wet ground

Additional comments

Echinodorus is an extremely popular genus of plants in the aquarium hobby. There are 30 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 bisexualbisexual:
(adj) having both male and female sexual reproductive structures on one individual or in one flower
flower, always of three petals and three sepals.