Echinodorus horizontalis

Description

Leaves 25 – 40 cm long, blades join the petiole at an obtuse angle so that they stand nearly horizontally, they are ovate or cordate, on the tip acuminate, the base truncate or shortly lobate, usually with 7 veins, 10 – 17 cm long x 5 – 8 cm wide. Stem recurved, proliferous, 25 – 60 cm long. Inflorescence racemose, having 2 – 4 whorls containing only 3 – 6 flowers each. Bracts shorter than pedicels. Pedicels 1 – 1.5 cm long, sepals ovate, membraneous, 4 – 6 mm long, having 18 – 24 ribs. During ripening the sepals enlarge and cover partly the aggregate fruit. Petals white, ovate, corolla 1.5 – 1.8 cm in diameter, stamens 26 – 30. Anthers oblong, 5 – 10 x shorter than filaments. Aggregate fruit globular, 0.7 – 0.9 cm in diameter, achenes 3 mm long x 1 mm wide, having 3 – 4 ribs and usually 6 glands in 2 rows. Young leaves are red and brown, older leaves green.

Cultivation

Deep, bed of rich substrate. Plenty of light and water on the soft, acid side. Tropical temperatures. It will grow well emerse or submerse. Propagate by adventitious plantlets which form on the inflorescence. A rather demanding species, now rarely seen.

The flowers open in the later morning hours only for about 2 hours. After this, it closes completely. E. horizontalis opens its flowers even under water. The plant is self-fertile.

Seed germination seems variable, but Rataj & Horemann report most success at higher temperatures (28 C).

Without flowers it can be confused with other species such as E. tunicatus, and rarely seems to be offered as the true species in the trade.