Black Tree Fern

Cyathea medullaris

Physical Characteristics

Cyathea medullaris is an evergreen Fern growing to 9 m (29ft) by 6 m (19ft) at a slow rate. See above for USDA hardiness. It is hardy to UK zone 9 and is frost tender. It is in leaf all year. Suitable for: light (sandy), medium (loamy) and heavy (clay) soils. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils. It can grow in semi-shade (light woodland). It prefers moist or wet soil.

Distribution

Australia, New Zealand.

Habitats

Woodland Garden Dappled Shade; Shady Edge; not Deep Shade; Bog Garden;

Edible Uses

Edible Parts: Leaves Stem Edible Uses: Pith of stem - raw or cooked[46, 61, 154, 173, 193]. Rich in starch, the portion below the growing point is the part used[193], do not confuse this with the trunk of the plant, which is made up of a peaty substance from the decaying roots[K]. The pith is used as a coarse sago substitute[2]. The pith contains (dry weight) 3.6% protein, 7.4% starch, 3.1% lipids and 3% simple reducing sugars[173]. The stem is often damaged some time prior to harvest in order to improve the flavour of the pith, a slimy red bitter gum exudes from the wound[173]. Harvesting the stem kills the plant and so cannot normally be condoned[193]. Base of the frond stems - cooked. Young new croziers - cooked[173]. Harvested just before they unfurl, they are juicy and slimy, tasting somewhat like bitter celery[193].

Medicinal Uses

None known

Known Hazards

Although we have found no reports of toxicity for this species, a number of ferns contain carcinogens so some caution is advisable[200]. Many ferns also contain thiaminase, an enzyme that robs the body of its vitamin B complex. In small quantities this enzyme will do no harm to people eating an adequate diet that is rich in vitamin B, though large quantities can cause severe health problems. The enzyme is destroyed by heat or thorough drying, so cooking the plant will remove the thiaminase[172].