Adiantum tenerum aka Brittle Maidenhair

Adiantum tenerum is a fern in the Pteridaceae family. It is perennial, so it lives for more than one year. People call it brittle maidenhair fern or black-stick maidenhair. It grows wild in Florida, Mexico, and the Caribbean. Its native range also spans tropical Central and South America. It grows on damp limestone ledges in warm, shaded sites. People have brought it to parts of Asia. They have also brought it to Pacific islands, including Hawaii.

Garden plants reach 1–1.5 feet [0.30–0.46 metres] tall. They spread 1–2 feet [0.30–0.61 metres] wide. Their growth is slow. Rhizomes support the plant's loose shape. Its fronds arch and trail. Thin, black, wiry stems contrast with light green leaves. Each smooth frond has a broad blade shaped somewhat like a triangle. The blade is three times pinnate, or split into many small parts. Fan-shaped leaflets have rounded tips with lobes and narrow cuts. Their brittle texture gives the fern one of its names. This fern has no flowers or fruit. It makes spores beneath flaps along the leaflet edges.

Grow this fern in bright, indirect light or shade. Direct sun can burn its fine leaves. It needs moist soil that lets excess water drain away. A peat-based potting mix with sand or perlite suits it. Use acidic soil rich in organic matter. Water once the top inch of mix feels dry. Do not leave roots in wet soil that drains poorly. The source recommends temperatures of 60–75°F and humidity of 50–70%. Keep plants out of cold drafts. Avoid sharp changes in temperature, too. Its listed outdoor hardiness range covers USDA zones 9–11.

In warm regions, use it in beds or borders. It also suits shaded sites beneath taller plants. Use it as groundcover or as a single specimen. Its arching fronds can soften a pot's edge. In colder regions, grow it indoors rather than outside. Display its fine leaves in pots, hanging baskets, or terrariums. It suits homes and offices that meet its growing needs. Division is the recommended way to make more plants.

NC State calls this fern easy to grow. It also notes that the plant needs little care. Even so, check the fronds for spider mites and aphids. Too much water or poor drainage can cause root rot. Its deer resistance helps where deer limit plant choice. The supplied sources give no food-use or toxicity evidence for this species. They do not establish whether this fern is safe to eat.