World’s biggest Tree Fern and the tallest Cycad together

King Fern - Angiopteris evecta

Angiopteris evecta (the Giant or KIng Fern) is an ancient species with reputedly the largest fronds of any fern on earth.  The species was thought to be extinct in the wild in New South Wales (NSW) until a single specimen was recorded in the far north-east of the State in 1978. The Giant Fern is the only species of the genus Angiopteris found in Australia.  NSW has commenced a recovery program to re-insert this marvellous plant back into the environment where it once lived.  In North Queensland Angiopteris evecta is commonly known as the King Fern and is not endangered, but still considered to be a prize among the fern family as the most primitive tree fern in existence and surviving naturally in the Wet Tropics of Queensland for at least 300 million years.

The King Fern (Angiopteris evecta) has either leaves tufted near ground level, or an erect rhizome forming a massive, woody trunk up to 1 metre in diameter and 3 metres in height in older specimens.  The leaf stalks are green, smooth and swollen at the base where a pair of dark cockle-shell like containers enclose the base. The bi-pinnate fronds are massive, up to 8 metres in length, and are reputedly the largest fronds of any fern on earth.

Angiopteris is a primitive genus and represents an ancient flora of Gondwanan origin.  Fossilised Angiopteris-like ferns dating from the early Mesozoic, some 200 million years ago, have been found at Lune River in Tasmania, when Australia was still part of Gondwana and a warm, wet climate prevailed.  During the slow drift north, the species was confined to warm and wet refugia such as the Daintree Rainforest.

The King Fern is a member of the Family Marattiaceae  (order  Marattiales).  The  genus Angiopteris contains approximately 100 species occurring in Madagascar, south-east Asia, Japan, Australia and the south-west Pacific.  Angiopteris evecta is the only species in this genus that occurs in Australia.  Finding this plant during a walk up the creeks feeding into Cooper Creek in close proximity to a Lepidozamia hopei, another Gondwanan relict, reminds us that we are definitely in a living museum.

Lepidozamia hopei

This specimen is quite small, but out in the open beside the creek it presents a rare opportunity to photograph the whole plant.  Lepidozamia hopei or Hope’s cycad  has a solitary palm-like stem and can grow to 20 m tall.  It occurs naturally in North Queensland between Cardwell and the Bloomfield River.  It is distinguished by the pinnate leaves which have pinnae from 15-30 mm wide with more than 15 parallel veins per pinna. There are separate male and female cones.  Our recent studies inform us that the female cone is able to emit a biochemical when it is pollenating that causes the male cone to turn up its temperature to discomfort the beetles (thrip) that inhabit the male cone.  Stimulated by the 12 degrees increase in temperature, the thrip, which predate flying insects, walk their burden of pollen to the female cone to effect cross-pollenation.

Cooper Creek Wilderness has a cycad that’s about 15-metres tall and an estimated 1,500 years old.  In the same area the world’s most primitive fern, psilotum nudum stands on the roots of the fan palms, Licuala ramsayi. Such primitive antiquity, representing the continuity of the world’s oldest rainforest, are the living fossils of the ancient Gondwanan landscape.

Has World Heritage listing given the protection that this prestigious area requires for its survival or is the Daintree Rainforest at risk?

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