Echinodorus horizontalis

Description

Echinodorus horizontalis is a medium-sized sword plant native to the Amazon depression in northern South America. It typically grows on shaded ground in marsh woods or temporarily flooded forests, where it experiences rapid changes in water level. When submerged, its leaves retain their same form as those when grown emersed. This species was once widely distributed in the aquarium hobby but is now rarely cultivated and can be hard to find in trade, often being misidentified as other species or hybrids. E. horizontalis has specific requirements for cultivation, being susceptible to fungal diseases and having a lower reproduction rate than many other sword plants when grown emersed. However, it grows well when cultivated submersed in an aquarium and forms flower stalks with adventitious plants. The leaf blades of E. horizontalis grow horizontally, are longish-oval with a heart-shaped base and acute tip, and have a gridlike pattern formed by transparent areas. The leaves are light to medium green, relatively firm, and rigid, with new leaves often having a reddish-brown color. The emersed inflorescence has few whorls, and the flower stalks lie down shortly after sprouting, forming only a small number of adventitious plants. In an aquarium, E. horizontalis grows to 15-20 cm high (maximally 35 cm) but its leaf rosette can reach 30-50 cm in width, occupying significant space. Its growth is relatively slow, taking several months to reach its full size. This species requires low light levels and prefers softer, slightly acidic water with a good supply of CO2 and a nutrient-rich substrate. An iron deficiency can cause chloroses to develop soon if left untreated.