Page 372 - Encyclopedia of Aquarium and Pond Fish, 3rd Edition

370 POND PLANT DIRECTORY

OXYGENATORS

These plants, which grow beneath the water’s surface,
play a crucial role in creating a healthy environment
for pond fish, because they release oxygen into the
water as a by-product of photosynthesis. They also
help to maintain water clarity by competing for
dissolved nutrients with particulate algae (which
are responsible for the green hue of pond water).
Some species also produce highly attractive
flowers. Oxygenators can, however, become
rampant, and it may be necessary to
remove clumps to ensure that the fish
have adequate swimming space.

Bubbles of oxygen stream from the leaves of Canadian
Pondweed (Elodea canadensis). Bubbles produced by
oxygenators can be seen rising to the surface of ponds
on sunny days when the water is calm.

Ranunculus aquatilis Myriophyllum spicatum Elodea canadensis
Water Crowfoot Eurasian Water Milfoil Canadian Pondweed

ORIGINS Occurs naturally in parts of North America ORIGINS Grows widely in parts of Europe, Asia, and ORIGINS Naturally occurs in North America, but now
and Europe. North Africa; a similar species exists in the US. established in Europe.
SIZE Grows in clumps up to 3 ft (1 m) in diameter. SIZE Strands may reach 10 ft (3 m) in length. SIZE Strands can easily grow to 12 in (30 cm) or more.
WATER Grows well in both flowing and still water. WATER Plant up to 3 ft (1 m) deep, in brackish and fresh WATER Thrives in clear water in a sunny position. Hardy
Hardy to –20°F (–29°C). water. Hardy to –30°F (–34°C). to –20°F (–29°C).
PROPAGATION Take stem cuttings during the growing PROPAGATION Take stem cuttings from established PROPAGATION Break off pieces about 6 in (15 cm) from
season, or sow seeds in late summer. plants in spring or summer. the growing tip. Does not need to be planted.
This member of the buttercup family has two leaf The relatively small, dark green leaves help to
forms: finely segmented leaves that grow underwater, distinguish Canadian Pondweed from similar
and broader ones that float on the surface. Its species. Pondweed grows readily, especially during
flowers, which are white with bright buttercup- the warmer months of the year, and is sufficiently
yellow centers, are often held above the water. hardy to survive the winter outdoors in temperate
As with other oxygenators, cuttings of Water areas. Pondweed is sold as sprigs that simply need
Crowfoot can be rooted in containers set on the to be attached to a weight so that they sink to the
pond floor. Start them off on the marginal shelf bottom. The sprigs will soon start to grow and
(see p.364) and then move them to deeper water. provide a valuable refuge for young fry.

Eurasian Water Milfoil spreads rapidly, forming
dense thickets that look attractive in shallow water.
Its delicate whorls are usually green but sometimes
have a reddish hue. The plant may produce small
yellowish-white flowers during summer. Eurasian
Water Milfoil is an invasive plant that can clog rivers
and lakes with dense mats of vegetation, and it
should never be released into natural waterways.

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