Improving on Nature: Hybrids and Cultivars

By Robert Paul Hudson

Outdoor gardeners have long appreciated the beauty of hybrid roses, begonias, and countless other man made strains featuring colorful plumes and varying shapes. Commercial growers of aquarium plants have brought us many attractive variations of Natures’ own beauty as well. In the early 1980s nurseries began experimenting with cross breeding Echinodorus species to create new variations for unique coloring with the goal of being faster growing and easier to keep. Some suitable hybrids were discovered and became popular staples of the hobby. This practice was continued with other plant genus. Major growers in the USA, Europe, and Asia have all developed hybrid/cultivars. The largest number have come from growers in Europe and Asia such as Hans Barth, Dennerle, Tropica Plants of Denmark, and Oriental Aquarium of Singapore. Some cultivars make a considerable contribution to the protection of natural species by providing an alternative that has more rapid growth for mass production and a more desirable appearance.

Sometimes these cultivars are the result of an accidental mutation. The “Oriental” sword is said to be a spontaneous mutation, which appeared during the in vitro culture of Echinodorus “Rose” in the aquatic plant nursery Oriental Aquarium of Singapore resulting in the name “Oriental”. The crossing of two species happens in nature as well the lab and continues to produce attractive new varieties for hobbyists. The “Red Rubin” sword was the result of cross breeding between Echinodorus horemanii red and the E. x barthii by the grower Hans Barth. Hygrophila polysperma var tropic sunset was patented in 1985 by Florida Aquatic Nurseries, and became one of the most popularly used plants in the hobby because of its rapid growth under most any tank conditions and its bright pink coloring. In recent years its rampant growth capability has made it a federal noxious weed in the United States.

Two hobbyist favorites are the E. red rubin for the tall strap like leaves which are dark red with yellow veins, and the Horemanii red with a similar leaf shape but much darker red. Others include the Ozelot, the Oriental, the Red Flame, the Kleiner bar and the Indian red. The lesser known Schlueteri leopard sword is an interesting cultivar that features oval shaped leaves with red spots, and usually only reaches a maximum height of twelve to fifteen inches. It does not readily reproduce, which makes the plant more difficult to find commercially. Some Echinodorus hybrids, such as the “leopard”, “parviflorus var tropica” and the “harbich” were developed specifically to be smaller in size than the original parents, making them more attractive to a variety of aquarium sizes.

The west African Anubias genus has long been used in the aquarium for their ability to tolerate low light conditions and for their attractive thick fleshy looking leaves. All Anubias species are rather undemanding to grow in the aquarium, making them a good choice for new hobbyists. Only those species that are too big for the aquarium are unsuitable. New Anubias cultivars are becoming accessible to the hobbyist. A cultivar is achieved by genetic manipulation and selective tissue culture to carry on certain traits such as leaf shape, size and coloration. Anubias nana, which is the smaller round leaf variety of Anubias barteri, now has several variations of its own. Anubias nana “petite” is the smallest with thumbnail size leaves.

Petite nana may be used quite effectively in small aquariums as a foreground plant, and may be planted either in the substrate or attached to wood or rock. The leaves grow in thick clusters on small creeping rhizomes. As the plant matures and is propogated, new leaf growth may be normal “nana” size as the mutation is lost.

Other new Anubias nana cultivars include “stardust” which has a white-powdered looking stripe down the middle of each leaf, the “narrow leaf” which has more slender leaves that come to a point, and “marble-leaf”, or “variegated” which are a swirl of green and white.

Microsorum pteropus, known as “Java Fern”, is one of the most widely used plants because of its tolerance of low light conditions. It has two cultivar versions originating from Tropica Plants of Denmark. The “Windelov” cultivar, named after the owner of Tropica Plants and sometimes called the “Java Lace fern”, is characterized by lacey fronds at the end of the leaves, while the “Tropica” cultivar is a large leaf variety with a more triangle shape and deep sinuate. Both were derived from culture of the same parent plants collected in Java.

Choosing your cultivars

The criteria for choosing your cultivar is the same as choosing any plant for your aquarium—size and growing requirements. Many wild species of Echinodorus ultimately grow very large and are suitable only for large aquariums. However, some cultivar species range from fairly small to moderately large. Many of these plants that feature dark red coloring are ideal as the primary focal point of the aquascape design, and really stand out in the rear of the aquarium. Smaller species may be used as accents or fillers in the middle of the aquascape. Light requirements for most Echinodorus are moderate and respond well to substrate fertilization and well-aged substrates rich in mulm. This makes them ideal for new hobbyists who are reluctant to invest in expensive lighting and C02 systems. It is best to plant Echinodorus at least four to six inches apart. Try to find out what the average mature size of the plant is before purchasing it, or be prepared to remove it the plant in six to twelve months if it becomes too large.

As previously stated, Anubias species are a good choice for new hobbyists because of their tolerance of minimal light conditions. The cultivar species range from quite small to moderate size and are usually used as an accent foreground or middle-ground plant in large aquariums, or a background plant in small aquariums. These plants grow very slowly, so faster growing plants that are too close could overgrow the Anubias.

Hybrid/cultivars that have not become commonly available are becoming more accessible to hobbyists from stores and online dealers that specialize in imported plants. As interest is growing more cultivars are being developed. Terrestrial and pond plant hybrid/cultivars have long received special recognition and awards from botanical societies. No such recognition exists for aquarium cultivars, but there should be! Many hobbyists are becoming interested is collecting various cultivars from a specific genus such as Echinodorus. I take a great deal of pride in my collection of cultivars and hybrids, particularly those that are difficult to find. It adds a whole new dimension of beauty and appreciation to the hobby of aquarium plants.

This article originaly appeared in Aquarium Fish Magazine, 2006