The Mud King: Echinodorus cordifolius

The Mud King: Echinodorus cordifolius

Author: Phillip Brown

A look at the different varieties of Echinodorus cordifolius, a large-growing focal point for the planted aquarium.

A big plant forms a centerpiece in the aquarium, creating a focal point to draw the attention of even the most casual of passers-by to the tank. One such plant that can be perfect for this role is Echinodorus cordifolius, known commonly as creeping burr head, radicans sword (based on its old incorrect name of Echinodorus radicans), spade leaf sword, elephant’s ear, or Texas mud baby. However, considering its size, “mud baby” doesn’t quite do it justice—instead, I think this beautiful species should be called the “mud king.”

This plant has a long history, first being described in 1753 as a species of Alisma (water plantain) and moved to the genus Echinodorus in 1857. It has long been grown in aquariums for its attractive leaf shape and its robust and hardy nature.

LOCATION AND COLLECTION

It is found as far north as Indiana, Illinois, Kansas, Missouri, and Oklahoma, but it’s often located in the warm southeastern states, Mexico, and northern South America. It is found naturally in marshes, swamps, and ponds, as it prefers a deep, rich, muddy substrate with light and room to grow. In some states it has become a weed.

Collecting plants from the wild is not a good idea. In some states or locations it may be illegal, and even if it is allowed there is still the risk of the wild plants carrying unwelcome visitors you will not want in your pond or aquarium.

GROWING TECHNIQUES

The mud king will grow well when completely submersed, but if well fed and in bright light (particularly if illuminated for over 12 hours), it will naturally try to grow above the water level. Most plants in the trade are grown emersed, and once completely submerged they may lose their leaves, though new ones will quickly grow back. If kept in a submersed state it should be put in a more shaded position (and illuminated for less than 12 hours a day) and kept starved. Pruning the roots regularly will also help keep it smaller. For the smaller aquarium, look for one of the smaller forms like ovalis.

Under reasonable conditions Echinodorus cordifolius can reach 4 feet (122 cm) in height with large leaves (a lovely dark glossy green in emersed plants, bright green in submersed ones). In the taller aquarium, floating leaves may form on long stems. The leaves are cordate to ovate with three to five prominent (lighter colored than the leaves) veins and pellucid markings (lighter colored transparent lines in the leaves). In good conditions, the large leaves can reach up to 16 inches (40 cm) long by 10 inches (25 cm) wide on stalks (petioles) sometimes up to 32 inches (81 cm) long. In color they are a medium to deep green, sometimes having darker markings in strong light. Leaf shapes can vary quite a bit. Emersed plants are very robust and have a darker glossy green color.

In the aquarium these plants will tolerate a wide range of temperatures, 10° to 27°C (50° to 81°F), but grow stronger and faster in the higher ranges. The pH and hardness values are not critical but algae growth on the leaves can be an issue in nutrient-rich, well-lit aquariums. Additional CO2 boosts growth which you may or may not want.

Plants can be grown in or by the pond (or even make an attractive conservatory plant) in warmer states (with no frost) and will then flower in the late summer and early fall, producing rather large white flowers, 2¼ inches (5.7 cm) across on tall inflorescences with between 5 and 12 whorls of flowers. These flowers will set viable seed (which look like small nutlets) and can be planted in sand in humid conditions and shallow warm water. Otherwise the adventitious plants that form along the inflorescence can be snipped off (once they form a few roots) and planted out in the aquarium or emersed in warm, humid conditions.

PLANTS CARE AND TRIMMING

The rhizome becomes very thick with a dense mass of roots. The rhizome can be divided in mature plants, but this requires a strong knife. Trim the roots back, and then replant in a peat, clay, and sand mixture. If being grown in an aquarium with no fish you can use a light dusting of rooting powder. The mud king is a greedy feeder and in the aquarium it is best to pot it in a good mixture of peat and clay with additional plant feed. Use a 3- to 4-inch pot, as these plants grow quickly. For really superb emersed specimens, dig a hole about 8 inches (20 cm) across by 6 inches (15 cm) deep and fill with a mixture of peat, clay, and leaf-mould. Keep it wet, or at least damp.

It flowers freely in long-day conditions (12 hours or more of good light) and the inflorescences can reach 50 inches (127 cm) with 5 to 12 whorls on a strong-growing plant. At first it grows vertically but then starts to bend over until it becomes horizontal (a characteristic of this species), and while lying on the substrate it will take root along its length, producing new plants.

E. cordifolius doesn’t suffer from many problems and is easy to grow. If grown outdoors by the pond it will sometimes be attacked by insects, which can be generally just washed off. It makes few demands as to water conditions but prefers a higher temperature than some other Amazon swords, and it will eventually decline in cooler conditions. Some strains seem hardier than others, no doubt depending upon where the original stock came from. Leaves turning very light (or even starting to turn transparent) indicate a lack of micro-nutrients, and a commercial plant food should restore things to normal.

VARIETIES

There are several varieties of Echinodorus cordifolius offered in the trade. It is best to research each before making a purchase so you know which type is right for you and your setup.

·         Aureus: New leaves on aureus are yellowish and older ones are golden. Submersed it forms large, heart-shaped leaves. The plant used to be sold under the name Echinodorus cordifolius “gelb.” It is not easy to grow and maintain in its best form, but the leaves are really beautiful when properly grown. Another downside is that it is not the cheapest plant for purchase.

·         Ovalis: Ovalis is a small orbiculate plant whose low, wide growth makes it suitable for smaller aquariums. It is an easy-to-grow variety. Ovalis tend to reach a height of about 14 inches (35 cm) with a width of about 12 inches (30 cm).

·         Fluitans: Sometimes recognized as a sub-species, this variety has a rounded base and no pellucid markings on the leaves. It grows fast and can reach 16 inches (40 cm), but the leaves tend to lay along the water surface rather than grow above it like the main type does.

·         Marble Queen: Marble queen (radican) has an attractive, creamy-white, marbled leaf surface that tends to be lost in low-light conditions but that often looks splendid, particularly by a pond. It can look rather like a large Hosta. In the aquarium it tends to remain as a submerged plant longer than the type plant. They like good substrate, additional CO2, and a strong light to retain the marbling effect that is best seen in emersed plants grown in a bright light.

The marble queen was originally cultivated in Singapore but it is now sold by a number of outlets. It is somewhat smaller than the type plant, typically reaching 8 inches (20 cm) by 6 to 8 inches (15 to 20 cm). It is particularly efficient in forming new plantlets that can be planted out to form new plants.

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