Symbionts In The Shrubbery

coralloid roots of Encephalartos ferox
coralloid roots of Encephalartos ferox

Whilst scrabbling around on my knees this morning, mulching the front garden with chopped sugarcane, I noticed the biggest and best display of coralloid roots is currently bursting through the surface of the leafy soil.

A warm, moist end to summer encouraged my cycads’ seasonal production of coralloid roots. They’re rising through the surface, forming little mounded ‘reefs’ amongst the decaying ruins of my Encephalartos ferox cones. Growing within the uppermost, window-like layers of root tissue dwells a symbiotic alga, which fixes atmospheric nitrogen. Converting nitrogen into nitrates that nourish its host, the alga pays for its comfy lodgings and both benefit from the arrangement. By summer the coralloid roots have decayed.

My fifteen year old Encephalartos ferox, a boy, is really enjoying life. It rarely gets watered with excess recycled sewage water, and that’s only when the vegetable garden needs none, a rare occurrence.

Sheltered from wind and afternoon sunshine, and growing in well mulched soil, it gets a few handfuls of poultry manure when it’s growing in the warm seasons. Otherwise it gets little attention.

Jerry Coleby-Williams
10th May 2010


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