staghorn fern

Platycerium, Staghorn Ferns
Platycerium bifurcatum - National Botanical Gardens
Scientific classification
Kingdom:	Plantae
Division:	Pteridophyta
Class:	Pteridopsida
Order:	Polypodiales
Family:	Polypodiaceae
Genus:	Platycerium Desv.
Species
Platycerium andinum Platycerium alcicorne Platycerium bifurcatum Platycerium coronarium Platycerium elephantotis Platycerium ellissii Platycerium grande Platycerium hillii Platycerium holttumii Platycerium madagascariensis Platycerium ridleyi Platycerium stemaria Platycerium superbum Platycerium quadridichotomum Platycerium veitchii Platycerium wallichii Platycerium wandae Platycerium willinkii

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Platycerium is a genus of ~ 18 fern species in the Polypod family, Polypodiaceae. Ferns in this genus are widely known as Staghorn or Elkhorn ferns due to their uniquely-shaped fronds. This genus is epiphytic and is native to tropical and temperate areas of South America, Africa, Southeast Asia, Australia and New Guinea¹.

Close up of Elkhorn fern

Platycerium sporophytes (adult plants) have tufted roots growing from a short rhizome that bears two types of fronds, basal and fertile fronds. Basal fronds are sterile, shield or kidney shaped and laminate against the tree and protect the fern's roots from damage and desiccation.

In some Platycerium species the top margin of these fronds forms an open crown of lobes and thereby catches falling forest litter and water. Fertile fronds bear spores on their undersurface, are dichotomous or antler shaped and jut out or hang from the rhizome. The spores are born in sporangia clustered in large sori that are usually positioned on the lobes or at the sinus between frond lobes.

Some species of Platycerium are solitary having only one rhizome. Other species form colonies when their rhizomes branch or when new rhizomes are formed from root tips. If the conditions are right the spores will germinate naturally on surrounding trees. Platycerium gametophytes are a small heart shaped thallus.

Platycerium have diverged into four natural groups³. Several Platycerium are strongly adapted to xeric conditions and the drought tolerating mechanism Crassulacean Acid Metabolism has been reported for P. veitchii³.

Platycerium superbum

These oddly-shaped ferns can be found in gardens, especially tropical gardens. Staghorns can be propagated by spores produced on the underside of the fertile fronds. Colonial Platycerium can also be vegetatively propagated by carefully dividing large healthy ones into smaller, separate plants. These new plants can then be strapped to trees with an old stocking until they take to the tree themselves.

A mature staghorn can grow more than a meter wide. When positioned well, Platycerium species are able to add privacy and a natural look to a garden.

References

1. Hennipman E & Roos M. C 1982 A monograph of the fern genus Platycerium (Polypodiaceae). Verhandelingen der Koninklijke Nederlands Akademie van Wetenschappen, Afdeeling Natuurkunde, Tweede Reeks 80: 1-126

2. Holtum J. A. M & Winter K 1999 Degrees of crassulacean acid metabolism in tropical epiphytic and lithophytic ferns. Australian Journal of Plant Physiology 26: 749-757

3. Kreier H. & Schneider H. 2006 Phylogeny and biogeography of the staghorn fern genus Platycerium (Polypodiaceae, Polypodiidae) Am. J. Bot. 93: 217-225