Alsophila spinulosa is a famous tree fern species of Cyatheaceae. Commonly known as the “living fossil”, it thrived about 180 million years ago. Alsophila spinulosa and dinosaurs are the two symbols of the reptile age.

Protection class

It is a Class II national key protected wild plant. It is also listed as Near Threatened (NT) on the IUCN Red List of Threatened Species and the China Plant Red Data Book; and listed on CITES Appendix II.

Distribution and habitat

Alsophila spinulosa is widely distributed in Hainan, including Wuzhishan and Baoting.

In China, particularly, the population of Alsophila spinulosa covers areas from 18.5°N to 30.5°N, with the northernmost record locating in Linshui County, Sichuan Province. Alsophila spinulosa likes warm and humid habitats in the mountain stream or open forests at an altitude of 260-1,600 meters. It often occurs in dozens or hundreds of trees as the dominant species, or scatters around the shrubs at the forest edge.

Morphological characteristics

The trunk is up to 6 m or taller, 10-20 cm in diameter, with persistent stipe at the upper part, and densely covered by adventitious roots downward. Its fronds are spirally arranged at the top of the stem. The end of the stem segment, the base of the rolled-up leaves and the stipe are densely covered with scales and pityroid scales that are dark brown, shiny and narrowly lanceolate, with setaceous brown apex and pale and thin toothed margins. The stipe is 30-50 cm long, usually brown or pale in the upper part, with sharp prickles along leaf axis and stem, and discontinuous lenticels on each side of abaxial surface extending upward to leaf axis. Fronds are 3-pinnate-pinnatifid and oblong (1-2 m × 0.4-1.5 m). Alternate pinnules are in 17-20 pairs, with one pair of basal pinnules shorter (30 cm long) and middle ones oblong (40-50 × 14-18 cm). Pinnules are in 18-20 pairs, with basal pinnules shorter, middle ones lanceolate (9-12 × 1.2-1.6 cm), base cuneate, sessile or shortly stipitate, apex long acuminate and caudate, pinnatisect. Pinnule segments are in 18-20 pairs, with an ascending posture, basal segments shorter, middle ones falcate, up to 7 × 4 mm, margin dentate, apex acute or mucronate. Veins are pinnate, with small ones under the base extending from the base of middle veins. Lamina is papery, green when dried up. The adaxial side of rachis, costa, and midvein are densely hairy with small pale scales. Sori are at forks of lateral veinlets and near the midvein, with septate silk and raised receptacle. Indusia are globose, thin and membranous. It is dehiscent outside and fragile, and reflexed over the main vein at maturity.