Cyathea medullaris or Black Tree Fern is a large tree fern which is only slightly hardy and will not survive frost, except in particular micro-climates with adequate care.
It should be overwintered in a cool greenhouse.
It is a fast grower and its black shiny leaf base and size make it a dramatic landscape plant.
Cyathea medullaris is an evergreen fern that reaches up to 20 m high. Its trunk is slender and black, covered with distinctive hexagonal stipe scars. It can attain 60 cm in diameter at the base
The fronds may be up to 5 m long, they arch upwards from the crown. The upside of the frond is dark green and shiny, the underside is a paler green. The primary pinnae are from 40 cm to 1 m long, and the undersides bear scales with marginal spines. New fronds form a fiddlehead and are covered in thick black hair.
The trunk is used as building material.
Black tree fern, king fern, mamaku, katātā, kōrau or pītau (Maori)
Alsophila extensa, Alsophila lunulata, Cyathea affinis, Polypodium medullare, Sphaeropteris medullaris
Cyathea: from the Greek kuathos (cup)
Medullaris: from the Latin medulla (marrow, pith)
New Zealand, Fiji, Polynesia
Lowland forest, from 0 to 600 m altitude
USDA zone 9, -4 °C
Well drained, humus-rich soil
Partial shade, shade
Keep moist, water daily in summer
- any time of the year
- surface sow in a light position, the spores need daylight at all stages
- 20-25 °C
- keep moist at all times, eventually place in a plastic bag to avoid evaporation of water
- germination time: 1-6 months
- partial shade, keep out of direct sunlight
- keep roots and the trunk wet at all times
- can easily be grown in a pot
- may be kept outside during summer but has to overwinter sheltered from frost, in a cool room or cool greenhouse