DRYNARIA.
Drynaria is a fern genus of the family Polypodiaceae. This family also includes the very different Staghorn and Elkhorn ferns of the genus Platycerium, and several other genera of mostly small creeping ferns. Like Platycerium, Drynaria has highly differentiated normal and basal fronds (foliage and nest-leaves). The basal fronds are sterile and much smaller than the others. About twenty species are known from Australia to China, the Pacific and Africa. Three occur in Australia.

Drynaria rigidula, Basket Fern.
This species is very adaptable, with a number of growth habits. It grows on trees in rainforest and tall open forest, where it can form huge colonies high in the canopy. It grows on rocks in more open areas, where it can form huge clumps. It grows as a much smaller plant sporadically amongst rocks in open forest. Here it is probably kept from developing into big clumps by regular fire, whereas in other rocky spots where large plants develop, it is in fire sheltered localities. And, finally, it grows in the ground in poor sandy soil of old dune formations, such as those of Edmund Kennedy National Park and Hinchinbrook Island. This form is a little different from the others in having considerably larger basal fronds. It may be taxonomically different.

In the forms that grow on trees and rocks, the basal fronds tightly overlap to create a basket or plant-pot in which the fern produces humus from the breakdown of its own matter. This attracts worms and various other soil fauna which bring in other nutrients.

The leaves are pinnate and about 1 metre long. The ground-dwelling form can have leaves up to 2 metres tall. The sori (spore-bearing spots on the undersides of the fronds) are arranged in single rows on either side of the midrib of the frond segments.

It is widespread throughout eastern Queensland and north-eastern New South Wales, and extends north into Malaysia.

Drynaria quercifolia, Oak-leaf Basket Fern.
This is a widely distributed and common fern found on trees or rocks in northern Australia. It usually occurs in fairly sunny, humid situations. In dry areas, the plants become deciduous during the drier part of the year and grow new fronds during the wet season. It sometimes grows in large, spreading colonies, especially in sandstone crevices.

The nest leaves are up to 40 cm long, very broad, lobed, and narrowed at the base, similar to the leaves of an Oak Tree, hence the common name. The normal, fertile leaves are very large, to about 100 cm long, and deeply lobed almost to the central vein. The sori are in a regular row on each side of a main secondary vein.

This is a very easy fern to grow in tropical and subtropical areas. It can be grown as a garden plant amongst rocks, or in a pot or basket of coarse mixture, or may be attached to trees. It is very frost tender.

Drynaria sparsisora.
This fern grows on rocky scree slopes and occasionally on trees. It can form considerable clumps, but is more commonly scattered amongst the rocks. The leaves are pinnatifid, being about 60 cm tall. The sori are small and scattered.

It is known from about Bundaberg north to Malaysia and is often found amongst rocks along streams or growing on tree trunks in open forest or dry rainforest.

May be grown in a container of coarse mix, or attached to trees, or grown amongst rocks in the garden. Frost tender.

PLATYCERIUM.

Platycerium is a genus of very distinctive ferns in the family Polypodiaceae. Like Drynaria, they have two very different types of leaves - foliage and nest leaves. The nest leaves are even more highly developed than in Drynaria, growing tightly over each other, forming a plant pot at the base of the plant that holds moisture and accumulates organic matter. Soil is accumulated by the breakdown of the dead nest leaves, from leaf fall off the trees above, and from insects and other fauna that live in or frequent the base of the plant.

Platycerium, as with Drynaria, creates a niche for various invertebrates. Some vertebrates also live there, such as frogs and skinks. Various other epiphytic plants grow in the clumps. A couple of plants become almost restricted to this niche, such as the Strap Fern (Ophioglossum pendulum), which is an epiphyte on an epiphyte.

There are four species of Platycerium in Australia.

Platycerium bifurcatum, Elkhorn.
A large fern growing on trees. It occurs from southern New South Wales to Malaysia. It grows in rainforest and extends into nearby open forest, often growing on Casuarina trees. In New South Wales, it is more common growing on rocks.

The nest leaves are deeply lobed and the true (or foliage) leaves are semi-erect or nodding, becoming pendulous with age. They are slender and narrowly wedge-shaped at the base and fork into a number of lobes at the ends.

Plantlets grow from buds on the outer lower margins of the nest leaves and in this way the plants can grow into very large clumps. Sometimes they become so large that the host tree cannot support them and they fall to the ground.

It is very easily grown attached to a tree or rocks in the garden and is quite hardy.

Platycerium hillii, Northern Elkhorn.
This species is very similar to P. bifurcatum, with which it is still often confused. It is common on Cape York Peninsula and is found in north eastern Queensland as far south as Ingham. It grows on trees and rocks in humid, lowland rainforest.

The nest leaves are rounded and 10-25cm across. They are pale green, becoming brown and smooth, often with wavy margins. The true leaves are erect, or almost so, and broadly wedge-shaped at the base, dark green, forked several times at the tip and growing 0.5 to 1.2 metres in length.

This species is not common in cultivation, but can be grown easily in tropical and subtropical regions. It needs warm, humid conditions and can be grown on trees or rocks in the garden.

Platycerium superbum, Staghorn.
This is the largest and most spectacular species in Australia, with long, pendulous, much-branched foliage leaves. In fact it must be considered one of the most spectacular ferns in the world. It grows high in trees in rainforest from northern New South Wales to Malaysia. It will also grow on large boulders and rock faces.

This most impressive fern remains as a solitary clump, increasing in size, and can sometimes attain quite impressive dimensions. The foliage leaves can grow to 2 metres in length and are often borne in pairs.

This is one of the most popular native ferns and is grown from tropical to temperate regions. In warm areas it can be grown attached directly to garden trees. They are also grown attached to slabs of hardwood or tree fern. In temperate regions they should be sited in protected positions and kept dry over winter.

Platycerium veitchii, Silver Elkhorn.
This species grows in vine thickets in coastal and semi-coastal areas and further inland, such as Carnarvon Gorge, Blackdown Tableland and White Mountains. Its distribution ranges from northern Queensland to southern parts of central Queensland. It occurs in much lower rainfall areas than the other species and is restricted to rocks, growing on boulders, cliff faces and gorges in open forest and woodland, often in exposed situations.

It frequently forms extensive colonies, and looks quite spectacular with the foliage displaying a beautiful silvery sheen. The much-branched nest leaves are deeply lobed and covered with fine silvery hairs. The foliage leaves are erect or semi-erect, slender and very narrow at the base, and usually only forking once at the tips. All are covered in silvery hairs.

It is easily grown and hardy in the open and very drought and frost resistant. Does best in full or dappled sunlight and does not like conditions that are too shady.