Cyathea affinis is a variable species of tree fern native to Fiji, Samoa, the Cook Islands, Austral Islands, Tahiti, and the Marquesas Islands. The trunk of this plant is erect and 2–6 m tall. Fronds are bipinnate and 2–3 m in length. The rachis and stipe are pale to brown in colour, or flushed with red towards the pinnule rachis. The stipe is sparsely covered in narrow basal scales, which are pale to dark and have broad fragile edges. Characteristically of this species, the lowest one or two pairs of pinnae may be slightly reduced and occur towards the base of the stipe. Sori are located near the pinnule midvein and are partially or fully covered by indusia, which open towards the pinnule margin.
Cyathea alpicola is a species of tree fern native to central Sumatra, where it grows in montane rain forest at an altitude of 2000–2750 m. The erect trunk can reach 5 m or more in height. Fronds are bi- or tripinnate and usually 2–3 m long. They have a tendency to persist on the plant after withering, forming an irregular skirt around the trunk. This species has a spiny stipe, which is covered with a woolly layer of scales. There appear to be two forms with different scales; either dark glossy brown with a broad paler margin and fragile edges, or small, brown and finely fringed. Sori are covered by thin, fragile indusia and occur near the midvein of fertile pinnules. The closest relative of C. alpicola is thought to be Cyathea polycarpa, which differs by lacking spines altogether. Cyathea macropoda and Cyathea magnifolia may also be closely allied with this species.
Cyathea apiculata is a species of tree fern native to Sumatra, where it grows in montane rain forest at an altitude of about 1800 m. The trunk is erect and usually 5 m tall or more. Fronds are bi- or tripinnate and 2–3 m long. The stipe is pale, becoming darker towards the base. It is covered with dark scales with pale, fragile edges. Sori occur near the midvein of fertile pinnules and are covered by thin, very fragile indusia.
Cyathea approximata is a species of tree fern endemic to Madagascar. The trunk is erect, spiny and about 2 m tall. Fronds are bipinnate and usually 2 m long. They often form a crown of two whorls of about seven fronds each. Dark brown scales with a paler margin cover the stipe. Sori are round and occur near the fertile pinnule midvein. They are covered by thin, brown indusia, which are cup-like in appearance.
Cyathea archboldii is a species of tree fern native to New Guinea and Bougainville, where it is common in submontane rain forest at an altitude of 1000–3000 m. The trunk is erect and up to about 3 m tall. Fronds are bipinnate and 2–3 m long. The rachis may be purplish and has short spines and scales. The scales range in colour from pale to brown, to bicoloured and have fragile edges. Sori occur in two rows along each side of the pinnule midvein and are covered by firm indusia.
Cyathea biformis is a species of tree fern native to New Guinea and the Maluku Islands, where it grows against trees in mossy forest and rain forest at an altitude of 850–2200 m. The climbing trunk is very thin, only 1–2 cm in diameter, but can reach 3 m in height. The apex of the trunk is covered in scales. Two types of fronds are produced, simple pinnate fronds, which are sterile, and bipinnate fronds, which may be fertile. The stipe is smooth, glossy and very dark, almost to the point of being black. It is covered at the base with long, very dark scales that have a pale margin. Fertile pinnules are distinctly stalked and lobed. Sori occur in four pairs per pinnule lobe and lack indusia.
Cyathea brooksii is a species of tree fern native to Cuba, Hispaniola and Puerto Rico, where it grows on serpentine soils in shaded ravines, along streams, and on forested slopese at an altitude of 250–950 m. The trunk is prostrate and only about 6 cm in diameter. Fronds are pinnate or bipinnate and up to 2 m long. The base of the rachis is covered with blackish scales that have a paler margin. Sori occur in two rows, one along each side of the pinnule midvein.
Cyathea callosa is a species of tree fern endemic to Luzon in the Philippines, where it grows in midmontane forest. The trunk is erect and about 3 m tall or more. Fronds are bi- or tripinnate and 1–2 m long. The stipe is spiny and covered with scattered scales that are dark and have pale, fragile edges. Sori occur near the midvein of fertile pinnules and are covered by thin, pale indusia.
Cyathea camerooniana is a species of tree fern native to Sierra Leone, Cameroon, northern Angola and western Uganda, where it grows in montane forest at an altitude of 900–1200 m. The trunk is erect and 2–3 m tall. Fronds are pinnate and 2–3 m long. The rachis ranges in colour from dark to pale and has some hairs on the underside. The stipe is dark and is covered with scales throughout. Where scales have fallen, small warts are present. The scales are glossy brown and have a thin, dull edge. Sori occur at the forks of veins and are covered by thin indusia, which range in shape from cup- to saucer-like.
Cyathea cinerea is a species of tree fern endemic to Mindanao in the Philippines, where it grows in forest at an altitude of about 1000 m. The trunk is erect, up to 5 m tall and about 12 cm in diameter. Fronds are bi- or tripinnate and 1–2 m long. The stipe has long spines and scattered scales, which are either narrow and pale or wide and brown. Sori occur near the midvein of fertile pinnules and are covered by brown indusia.
Cyathea coactilis is a rare species of tree fern known only from the southern highlands of Papua New Guinea, where it grows in alpine shrubland at an altitude of about 3000 m. The trunk is erect and 2–3 m tall. Fronds are bi- or tripinnate and usually 1–2 m long. Characteristically of this species, they occur in two whorls of about ten fronds each. The underside of the rachis is covered with small, pale scales. The stipe is covered with pale scales that have dark, narrow and fragile edges. Sori are round and are covered by thin indusia that are cup-like in appearance. They occur near the fertile pinnule midvein.
Cyathea costalisora is a species of tree fern native to western New Guinea, where it grows on the edges of forest and in moist hollows at an altitude of 1900–3225 m. The trunk is erect, up to 4 m tall and may branch near the base. Fronds are bi- or tripinnate and 1-1.5 m long. The stipe is warty, especially where scales have fallen. The scales are pale and have a distinctive dark glossy central region, with a paler dull margin. Sori are round and occur near the fertile pinnule midvein. They are covered by firm, dark indusia that are cup-like in appearance.
Cyathea costulisora is a species of tree fern native to Sumatra. The trunk is erect and usually 1–4 m tall. Fronds are bi- or tripinnate and 1–2 m long. The stipe is covered with warts and scales. The scales are either pale and glossy or dark and flat. Sori occur near the fertile pinnule midvein and are covered by large, firm, brown indusia.
Cyathea dicksonioides is a species of tree fern native to northeastern New Guinea, where it grows in grassland at an altitude of 2600–2900 m. It is a relatively uncommon species. The erect trunk may be 3 m tall or more and about 20 cm in diameter. Fronds are bi- or tripinnate and approximately 1 m long. They are erect and bristly, forming an irregular crown. The fronds occur in two whorls of 10-12 fronds each, with the inner of the two whorls bending downward towards the trunk. The stipe is covered with glossy scales that have narrow, pale and fragile edges. Two to four sori occur per fertile pinnule. They are covered by firm, pale indusia that are hood-like in appearance.
Cyathea eriophora is a species of tree fern native to eastern New Guinea, where it grows in wet ravine forest at an altitude of 1400–2000 m. The trunk is erect and 2–3 m tall. Fronds are bi- or tripinnate and 2–3 m long. The stipe is dark and covered with spines and scales. The scales are variable, being either small and pale or large with a dark apex. Sori occur near the fertile pinnule midvein and lack indusia.
Cyathea everta is a species of tree fern native to western New Guinea, where it grows in the edges of forest or in mossy forest at an altitude of 1400–2800 m. The trunk is erect and up to 5 m tall. Fronds are bi- or tripinnate and 1-1.5 m long. Numerous fronds are present at any one time and form a dense crown. The stipe has some spines towards the base and is covered in scales. The scales are pale or dark, glossy and have pale fringed edges. Sori occur near the fertile pinnule midvein. They are round and covered by thin, brown indusia that are cup-like in appearance.
Cyathea ferruginea is a species of tree fern endemic to the Philippines.
Cyathea foersteri is a species of tree fern native to eastern New Guinea, where it grows in scrub in forest margins and mossy forest at an altitude of 1600–2800 m. The trunk is erect and up to 10 m tall. Fronds may be bi- or tripinnate and 2-2.5 m long. Usually around nine or ten live fronds are present in the crown at once. The stipe is covered in pale scales. Sori occur near the fertile pinnule midvein and are protected by firm, thin indusia.
Cyathea gleichenioides is a species of tree fern endemic to New Guinea, where it grows in open peaty grassland and on forest margins, often in groups, at an altitude of 2800–3700 m. The trunk of this plant is erect, up to 3 m tall and about 24 cm in diameter. The narrow fronds are tripinnate and about 1 m in length. Around 60 fronds form a rounded crown.The stipe is warty and bears scattered scales towards the base. These scales may be either glossy brown with a paler dull margin, or small, pale and fringed. Sori occur one or two per fertile pinnule and are protected by firm, brown indusia.
Cyathea imbricata is a species of tree fern endemic to Western New Guinea, where it grows in open forest at an altitude of 3240 m. The trunk of this plant is erect and approximately 2 m tall. Fronds may be bi- or tripinnate and are usually less than 1 m in length. The stipe is dark, spiny, and covered with caducous scales. These scales are glossy brown in colouration and have a paler margin and fragile edges. Sori are borne in groups of one to four per pinnule lobe. They are protected by firm indusia.
