Archive for the ‘Submerged (Oxygenating) Plants’ Category

Ceratophyllum demersum

Common name: Hornwort, Rigid Hornwort, Coontail, Coon’s tail

Family: Ceratophyllaceae

Ceratophyllum demersum

Ceratophyllum demersum

Distribution and habitat: Ceratophyllum demersum is native to North America but nowadays having a cosmopolitan distribution in temperate and tropical regions. Ceratophyllum demersum is declared weed Australia and is classed as an unwanted organism in New Zealand.

Description: Ceratophyllum demersum is a submersed with no roots,  so is free-floating perennial plant. The stems reach lengths of 1–3m (3-10 feet), with numerous side shoots making a single specimen appear as a large, bushy mass. The leaves are produced in whorls of six to twelve, each leaf 8–40mm (0.3-1.6 inch) long, simple, or forked into two to eight thread-like segments edged with spiny teeth; they are stiff and brittle. It is monoecious, with separate male and female flowers produced on the same plant. The flowers are small, 2mm (0.08 inch) long, with eight or more greenish-brown petals; they are produced in the leaf axils. The fruit is a small nut 4–5mm (0.1-0.2 inch) long, usually with three spines, two basal and one apical, 1–12mm (up to 0.4 inch) long. It can form turions: buds that sink to the bottom of the water that stay there during the winter and form new plants in spring.

Care: Ceratophyllum dersum grows in still or very slow-moving water. Generally floats during the warm months if allowed, but may be potted and submerged. Sinks to the bottom of the pond during cold weather if allowed to float. Ceratophyllum demersum is fast growing plant.

Light: Ceratophyllum demersum’s light requirement is part shade.

Temperature: Ceratophyllum demersum grows in lakes, ponds and quiet streams with summer water temperatures of 15-30°C (59-86°C) and a rich nutrient status.

Propagation: Ceratophyllum demersum natural propagate through seed that sink to the bottom of the water and stay there during the winter, forming new plants in spring.  Also  Ceratophyllum demersum  can be propagated from plant fragments.

Uses: Ceratophyllum demersum is often used as a floating freshwater plant in both coldwater and tropical aquaria, being free-roots plant or it may be attached to the substrate or objects in the aquarium. Its fluffy, filamentous, bright-green green leaves provide an excellent spawning habitat for fishes.

Interesting facts: Ceratophyllum demersum has allelopathic qualities as it excretes substances that inhibit the growth of blue-green algae (phytoplankton and cyanobacteria).

Ceratophyllum demersum may be confused with non-weedy Ceratophyllum echinatum, which is more delicate, bright green, usually grows in deeper water, and has 3-5 lateral spines on the fruit. Also Ceratophyllum demersum is similar to other bushy submersed plants such as: Muskgrasses (Chara spp.) which are large algae and produce a skunk or garlic-like odor when crushed; waterweeds (Elodea spp.) which have whorls of broad flat leaves; and milfoils (Myriophyllum spp.) which have feather-like leaves.

Note: Ceratophyllum demersum is an invasive species. Its dense growth can out-compete native underwater vegetation, leading to loss of biodiversity.

Hardiness Zone 4-10

Ceratophyllum demersum inflorescence Ceratophyllum demersum fruit







Aquarium Plants, Submerged (Oxygenating) Plants, Water Plants , , , ,

Egeria densa

Common name: Large-flowered Waterweed, Brazilian Waterweed, Elodea, Anachris

Family: Hydrocharitaceae

Synonymus: Anacharis densa (Planch.) Vict., Elodea densa (Planch.) Casp

Egeria densa

Egeria densa

Distribution and habitat: Egeria densa is an ageless aquarium plant, a species of Egeria native to warm temperate South America in southeastern Brazil, Argentina, and Uruguay and become naturalized and invasive in many warm temperate to subtropical regions of the world, including Europe, southern Africa, Asia, Australia, New Zealand and North America.

Description: It is an aquatic plant growing in water up to 4m (13 feet) deep, with trailings stems to 2m (6 feet) or more long, producing roots at intervals along the stem. The leaves are produced in whorls of four to eight, 1–4cm (0.3-1.5 inch) long and 2–5mm (0.7-2 inch) broad, with an acute apex. It is dioecious, with male and female flowers on separate plants; the flowers are 12–20mm (0.4-0.8 inch) diameter, with three broad, rounded, white petals, 8–10mm (0.3-0.4 inch) long on male plants, and 6–7mm (0.2 inch) long on female plants.

Houseplant care: Must be planted in full sun to avoid the lower leaves from rotting, submerged at the base of a waterfall where the water moves freely is ideal providing excellent filtration. It will not do well in still waters. It grows best in a nutrient rich, high light situation.

Egeria densa is an adaptable plant that can grow in both high light and low light conditions.  When grown in high light, Egeria densa stems will display a dark green and grow up to 0.5m (2 feet) long in a short matter of time.  It will appear very leaf due to the short distance between the internodes of the stem. In low light situations, the leaves and internodes along the stem will become more spaced out, the stem becomes thinner, and the plant will take on a dull green color.

Temperature: It grows well in the cooler aquarium and is very easy to grow.

Propagation: It is easily propagated through fragmenting the stem and side shoots. Plants in cultivation are all a male clone, reproducing vegetatively.

Uses: Egeria densa is a popular aquarium plant. Egeria densa is used to oxygenate the water and to absorb excess nutrients.

Egeria densa can be used in the background or midground areas of sparsely planted aquariums planted in bunches of 6-7 stems. It also does well floating.

Interesting facts:
It said that Egeria densa secretes anti-bacterial enzyme that can reduce blue-green algae (cyanobacteria).

It is often confused with similar looking species Hydrilla and Elodea Canadensis as per image bellow:



Egeria densa leaves are in whorls (leaf groups) of 4 to 5; Hydrilla leaves are in whorls of 4 to 8; and Elodea Canadensis forms whorls of 3.

Note: The rapid growing nature, couple with few predators and no diseases, has allowed Egeria densa to flourish in the wild unchecked.  Ponds, lakes and streams are in danger to become infected, large mats of Egeria densa that prosper block out the sun to the native vegetation, causing havoc on the local ecosystem and boaters. Take great care not to let this plant enter local waterways.

Hardiness zone:  5a-11

Egeria densa flower







Submerged (Oxygenating) Plants, Water Plants , , , ,

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