Epiphytes

An epiphyte is a plant or plant-like organism (eg. lichen) that grows on the surface of another plant and derives its moisture and nutrients from the air, rain, water or from debris accumulating around it. They do not harm the host plant. Epiphytic Australian native orchids include Cymbidium, Dendrobium and Sarcochilus species.

There are two types of growth found in epiphytic orchid plants. One growth pattern is called sympodial, the other is monopodial.

Sympodial orchids produce new shoots from the base of old ones. The stem called a rhizome in sympodial orchids grows horizontally. As it grows successive new shoots are put up with each one a duplicate of the one before. Parts of the stem will become thickened with stored water and nutrients these are known as a pseudobulbs. These structures allow the plant to become dormant during periods of drought. The Cymbidium and Dendrobium genera belong to this category.

Monopodial orchids grow continuously upwards from existing stems, and some reach many feet in height under ideal conditions. Monopodial orchids have alternate leaves the entire length of the stem. Lower leaves may fall off as the plant ages. Unlike Sympodial orchids monopodial orchid do not produce pseudobulbs and therefore cannot become dormant, making them less resistant to droughts. Sarcochilus and terrestrial orchids are examples of monopodial orchids.

Fig. 2. Sympodial vs Monopodial Growth strategies. A) Sympodial eg. Dendrobiums have multiple stems growing horizontally off the old stem; B) Monopodial eg. Sarcochilus have a single stem with alternate leaves.More stems may grow as the plant gets older.

Phalaenopsis rosenstromii is the only native Phalaenopsis. Also known as the Native Moth Orchid it is a mostly epiphytic plant with a single long, thick, flat root. The stems growing successively from the root can get to approximately 30cm and have 2–8 broad, fleshy, dark green leaves scattered along the stem. From December-April 2-10 large moth-like white flowers appear on stems with a white with yellow and red-brown streaks and bars in the labellum. Highly localised to the rainforests of north-eastern Queensland from Iron Range to Mt Spec. It likes humid conditions and grows predominantly on trees that grow on sheltered slopes, in gullies, in deep gorges or close to waterfalls and streams.

Phalaenopsis rosenstromii

Oberonia attenuata – commonly known as the Mossman fairy orchid as it is only found from the Mossman Gorge area of Queensland. As a small native epiphyte it has a pendulous stem from which successive shoots emerge with four and seven leaves growing in a fan-like arrangement. Large numbers of small reddish-brown flowers appear from May to September. The species was first formally described in 1960 where it was found growing on a rainforest tree near Mossman River. Despite multiple attempts no further sightings were made until 2015. Oberonia attenuata is therefore listed as Critically Endangered (Date effective 30-Apr-2016) .

Vanda hindsii – found at Cape York Queensland and commonly known as the native strap orchid or the Cape York Vanda, it is also found in New Guinea and the Solomon Islands. It is one of Australia’s largest monopodial epiphytic or lithophytic clump-forming orchids. It can be found in rainforests on tall trees in humid conditions near rivers or on rocky outcrops with very bright sun. It has lots of branching stems with many thick, leathery, strap-like leaves forming large clumps. Small shiny brown flowers with greenish to yellow markings and a white labellum from November to March.

Australian Native Orchids with a single species from an orchid genus.

A) Phalaenopsis rosenstromii ‘Moonshine’ AM/ANOS 1990 ANOS award (NSW)

B) Oberonia attenuata

C) Vanda hindsii

‘Name’ indicates cultivated variety, details and image available on ANOS Inc. award website. If there is no variety name it is a wild taken image.