The name of the genus Alsophila, is derived from the Greek alsos, meaning ‘grove’ or ‘glade’ and phila, meaning ‘loving’, referring to shady glades where ferns like to grow. This species is named after J.F. Drege, 1794–1881, a plant collector from Germany, who was exploring South Africa during 1826–1834. The former genus name Cyathea is derived from a Greek word kyatheion that means ‘little cup’ which refers to the shape of the structure that holds the spores, and can be observed by looking under the fertile fronds.

This species has moved from Cyathea to Alsophila, then back to Cyathea and now all African species that were Cyathea are back in Alsophila. The naturalized Australian species Cyathea cooperi, is now Sphaeropteris cooperi. However, they are all still called by their old name, Cyathea, in most of the gardening literature.

Cyatheaceae, the tree fern family, has about 7 genera with more than 700 estimated species worldwide. Alsophila dregei is one of 2 tree fern species indigenous in South Africa, the other being Alsophila capensis, the Forest Tree Fern, which occurs in deep forest near streams and in high rainfall areas from the Cape Peninsula to the Eastern Cape and northwards to East Africa. Exotic tree ferns are widely grown in gardens and a few have naturalized in some regions.

Ferns are unmistakable as they do not produce flowers or seeds, but reproduce by means of spores, which are found on the lower surface of their fronds. The spores are tiny; a microscope is necessary to see them. The spores are produced inside structures called sporangia, also called spore casings; a hand lens or dissecting microscope would help in order to see individual sporangia better. A cluster of sporangia, is termed a sorus (plural is sori). To the naked eye these are the puffy brown dots underneath the fern fronds. They are found under the leaf, sometimes in rows and sometimes along the leaf margins. In this species, up to 12 sori, in 2 rows, can develop on each pinna. This species, and many other ferns, protect their sporangia inside a colourless tissue, called an indusium (plural indusia). The spores mature when the leaf turns brown. The spores are dispersed by wind. When a spore lands in suitable conditions, it germinates and grows into a tiny group of flat, often heart-shaped cells that produces the male and female sex cells, this is called the gametophyte. If fertilization occurs on the gametophyte, a new fern plant develops directly from this structure, and this is termed the sporophyte. It will grow into a new fern plant.

The ferns first appeared in the fossil record from about 360 million years ago.