Psilotum nudum aka Whisk Fern

Psilotum nudum has two common names: whisk fern and skeleton fork fern. It stays green year-round and lives for more than one year. It belongs to the plant family Psilotaceae. Its native range covers much of the tropics and subtropics. This includes the southern United States, with records in North Carolina. Sources also list Central and South America, Africa, and the Far East. It grows on soil, among rocks, and on trees. In the wild, it grows in thickets and open woods. It also grows in clearings and cracks in cliffs.

The plant has a sparse form of green, forked stems. Sources give mature heights of about 1.7–2 feet [0.5–0.6 metres]. Stems stand upright when the plant grows in soil. They often hang down when it grows on trees. Each stem splits into paired forks and has three sides. Small, pointed growths sit far apart along the stems. These leaf-like growths, called enations, are much shorter than an inch. They have no hairs, and the stems have no scent. The plant has no true roots. It has short, creeping stems called rhizomes.

Whisk fern has no flowers and forms no fruit. It makes spores in small, round sacs along its stems. Three spore sacs join to form each structure, called a synangium. These structures look yellow and may take on brown tones. Their colour stands out against the green stems. The plant can also spread through its rhizomes. This spread helps explain why it grows as a nursery weed.

In gardens, whisk fern grows in sun or partial shade. One source favours a mix of sun and shade. Keep the soil moist, but let water drain well. Sources suggest soil rich in humus or a sandy growing mix. Slightly acid to neutral soil suits it. North Carolina State lists USDA hardiness zones 8a through 10b. Garden uses include pots, small spaces, and native gardens. It can also serve as a specimen plant. Plants on trees use their host for support, not food or water.

The plant needs little care, but unwanted spread can cause problems. It grows as a weed in nurseries. Its growth may also cause trouble in greenhouses. North Carolina State reports no known diseases or insect pests. Useful Tropical Plants records tea made from the whole plant. It also records the use of spores as a drying and dusting powder. That source lists no known hazards or uses as medicine. North Carolina State reports use as medicine but gives no details. These records do not show that it is safe for people or pets.