Treeferns

Please note: "treeferns" are not to be confused with ferns that grow in trees!!! These are called "epiphytic ferns" and are usually small, found commonly on mossy trees in rainforests. (Some even grow on treefern trunks!) A "treefern," on the other hand, actually is a tree in and of itself!. Technically speaking, however, they are not real trees, because true ferns do not develop a woody trunk that functions like other trees. All ferns have a rhizome, from which the fronds emerge. These rhizomes can vary (from species to species) from long to short, or be creeping along the ground, or inconspicuous, and so forth. A tree fern is simply a case of the rhizome being very long and strong enough to support itself.

Leaves of all ferns, including treeferns, are referred to as fronds. On treeferns, the fronds are held at the top of the plant in a spreading manner. They form by uncurling from the crown in the center, which is at the top of the trunk. (This terminology can be slightly confusing, since "crown" is often used loosely to mean the entire top of the plant, including the fronds. Also, with other plants, "crown" may mean something different still.) The crown might be considered the most important part of the plant, since that is where all the leaf growth comes from. If it is destroyed, no more croziers will emerge from it, and the rest of the plant will eventually die.

The frond bases, where they join the top of the trunk, are called stipes; and the fronds when they first begin to emerge and uncurl, and look like a snail's shell, are called croziers. The process of croziers uncurling and expanding to form fronds is really fascinating to watch, and makes tree ferns a lot of fun to grow. Usually it takes several weeks for the expansion of a crozier into a frond to be completed.

The trunk, really a very long upright rhizome, is the part which supports the crown and fronds. Its main roles are to elevate the fronds above competition from surrounding plants, and to transport water and nutrients to and from the fronds and crown. On many spcies, such as Dicksonia antarctica, the trunks are covered in a great mass of roots. Other species, parcticularly Cyatheas, have trunks of a more solid, almost woody substance and form fewer roots above ground level. The roots of all treeferns are small and do not thicken with age as do the roots of woody plants. A few treeferns form underground buds and can even send up runners some distance away from the parent. Such plants are able to recover if the main crown is destroyed, since essentially they have more than one crown.

All treeferns reproduce from spore. The spore develop in structures called sori on the undersides of the fronds. They are found only on mature plants, and when they are released they look like dust. The main method of treefern propagation is to raise them from spore. It takes most species 5 to 20 years before they are old enough to reproduce.

• treeferns grow There are perhaps nearly a thousand treefern species which grow chiefly in the Southern Hemisphere and the tropics. Many of these are quite cold-tender and will suffer if the temperature drops below freezing. But a few from Australia, New Zealand, Africa and some other places are cold-hardy enough to adapt to a less hospitable climate. The list of species on this page is by no means all-inclusive. In addition to these there are probably a number of other species and hybrids that are less well known but could grow in cooler climates. There seems to be a lack of information about tree fern species from South America and Mexico, some of which could be very promising for cool climates. The high Andes, where treeferns thrive up to 14,000' above sea level, and southern Brazil are especially promising places.

• Treefern classification The two main genera of hardy tree ferns are Cyathea and Dicksonia. Species of Dicksonia are readily identified by hairs growing on the newly emerging fronds and the most common Cyatheas can be identified by the presence of scales on many (but not all) species brown scales, white scales. Just because one has scales and one has hairs does not mean that one is a male and the other a female (as one of the contributors to this page was once told by a supposedly qualified nurseryman)! Cyathea formerly consisted of several genera, including Alsophila, Hemitelia and Sphaeropteris. Although they have since been joined, clear distinctions between each group are obvious, and some still regard them as subgenera.

Thank: angelfire.com