Microsorum 'Windeløv' and Microsorum 'Tropica'

by Claus Christensen and Ole Pedersen

Two new and very distinctive variants of the well-known Microsorum pteropus. Solitary plants for foreground use or small aquaria are a rarity.

Recent years have seen the appearance in the shops of many new aquarium plants. Large numbers of new hybrids have been created between known plants, particularly within the Echinodorus genus. A few plants have arrived from the wild - although these are not "new" as such, but rather specimens not previously used in aquaristics. A number of new varieties, whose precise origin is difficult to pinpoint, have also arrived. This category includes both natural and artificially induced mutations arising during tissue culture (here too the Echinodorus genus is strongly represented).
From the genus Microsorum, which numbers more than 40 species, just one has found widespread application in aquaria -Microsorum pteropus. This species has been used for several decades and exists in several varieties, some with slightly broader or narrower leaves and with minor differences in leaf colour. An extremely narrow?leaved fern, in all probability also a Microsorum, has also been available in the shops.

In 1991, Tropica Aquarium Plants of Denmark discovered two new varieties of Microsorum pteropus, "Java fern", both in plant cultures originating from a collection assembled in Java. The plants probably existed in the original plant material and must be assumed to represent a natural mutation. Large numbers of these new plants are unlikely to exist in the wild as no other discoveries of these varieties have been recorded either before or since.
An application for variety protection has been filed for both plants, and the authorities have accepted this application. Variety protection may be likened to a patent for plants, the effect of which is to restrict commercial production to licence holders. This restriction does not apply to ordinary aquarists who are naturally welcome to propagate these plants! (Application was filed in the names Microsorum pteropus 'Win' and Microsorum pteropus 'Trop' but the trade names will are the above-mentioned).

Microsorum pteropus 'Windeløv'
This graceful variety is named after Holger Windeløv, owner of Tropica Aquarium Plants, Denmark. The plant divides at the leaf tip into two branches, and often into two more branches immediately after. After 5-10 mm the narrow leaves divide repeatedly, each finely divided leaf forming a tuft. This gives the plant a highly distinctive appearance, unlike that of any other plant ever seen in an aquarium.
While relatively small in stature, rarely reaching above 20 cm in aquaria, the plant is characterised by bushy growth. It displays several novel features. Most solitary plants are tall. However, Microsorum pteropus 'Windeløv' is suitable both as a highly decorative plant for the small aquarium and as a solitary plant for foreground use in large aquaria!

Like other members of its genus, Microsorum pteropus 'Windeløv' develops young plants at the leaf margin. These adventitious plants assume the same characteristic appearance as the parent plant.Older leaves from sporangia on the underside of the leaf which resemble black spots. These are often taken to be signs of disease, but they are infact the normal reproductive organs of the fern plant.

Microsorum pteropus 'Tropica'
This species is named after Tropica Aquarium Plants of Denmark. The leaf margin is initially denate in shape. Later, the tooth-like projections become longer, and on old leaves may form relatively thin lobes. The leaves are reminiscent of those of the dandelion. Microsorum pteropus 'Tropica' has a more robust habit than the conventional Microsorum. On older plants the leaves may become as large as 30-40 cm. New leaves on older plants are often divided into three parts, which together with the lobes create an enhanced ornamental effect.
As with the ordinary Microsorum pteropus, adventitious plants form on the old leaves. This initially occurs at the leaf margins but may also take place on the leaf surface itself. Eventually a shower of plants may form. These adventitious plants do not acquire the characteristic leaf lobes of Microsorum pteropus 'Tropica', usually only a vague hint developing. To maintain the characteristic features of the plant these plantlets may be removed. Formation of sporangia has yet to be observed on this fern. Microsorum pteropus 'Tropica' is well suited for both background and solitary purposes in large aquaria.

A characteristic feature of both of these new plants is that they require the same aquarium conditions (except for the size requirements) as the well-known Microsorum pteropus. Both anchor themselves readily to stones and roots, as is the natural mode of growth of the genus Microsorum in the wild. When planting, secure the specimen to a root (for example with a rubber band or a fishing line), after which special crampon roots will develop. If planting in gravel, care must be taken not to bury the horizontal tubers (rhizomes). All Microsorum species make only very modest demands on the aquarist. They can withstand weak lighting (simply growing more slowly as a result). They can tolerate a wide range of water conditions, from very soft to hard and even brackish water. Aquarium temperature is only of secondary importance; the plants grow readily in temperatures between 20-30° C, lower temperatures merely slowing their growth rate. All things considered they must be about the hardiest of all aquarium plants!