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Psilotum spp.
whisk fern
Overview
Psilotum, the whisk fern, is a genus of two species of rootless, leafless vascular plants in the family Psilotaceae, related to ferns. Instead of true leaves and roots, it has slender green stems that branch repeatedly in a forked (dichotomous) pattern, growing 8-30 inches (20-75 cm) long and arching or hanging. Tiny scale-like outgrowths take the place of leaves, and photosynthesis occurs in the green stems. Reproduction is by spores produced in small, three-lobed yellow capsules (synangia) borne along the upper stems; the plant has no flowers, fruit, or seeds. P. nudum is widespread across tropical and warm-temperate regions, growing as an epiphyte in tree crevices or terrestrially in rock cracks and humus. The genus depends on warmth and humidity and is sensitive to frost and dry air. It is grown as a curiosity and, in some horticultural traditions, as a container plant. Underground stems host a symbiotic fungus that aids nutrient uptake.
Native Range
Psilotum is pantropical, occurring naturally across tropical and subtropical regions of the Americas, Africa, Asia, the Pacific, and Australia, reaching into warm-temperate areas such as the southeastern United States, Hawaii, and Japan. It grows on tree trunks, in rock crevices, and in leaf litter in warm, humid habitats.Suggested Uses
Grown as a botanical curiosity in greenhouses, terrariums, and shaded containers in warm climates. In parts of East Asia it is cultivated as a traditional ornamental in pots. It also grows as an epiphyte mounted on bark or in hanging displays.How to Identify
Appearance
Size & Dimensions
Height8" - 2'6"
Width/Spread8" - 1'6"
Reaches mature size in approximately 3 years
Bloom Information
Psilotum produces no flowers. It reproduces instead by spores released from small yellow synangia along the stems, mainly in the warmer months. The spores germinate into tiny underground gametophytes.
Detailed Descriptions
Foliage Description
greenGrowing Conditions
Sun Requirements
Requires 2-5 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Care & Maintenance
Care Guide
Grow Psilotum in warm, humid, frost-free conditions in bright, indirect light, sheltered from direct midday sun that can scorch the stems. Use a very open, free-draining medium such as a bark- or orchid-based mix, or grow it as an epiphyte on bark. Keep the medium lightly moist and maintain high humidity, as dry air causes stem tips to brown. Water with low-mineral water where possible, since the plant is sensitive to salt buildup. Feed sparingly with a dilute, balanced fertilizer during active growth. In temperate regions it is grown as a greenhouse or container plant brought indoors over winter.Pruning
Pruning is rarely needed for Psilotum. Dead or browned stems are cut back to a healthy fork to keep the plant tidy. Self-sown sporelings can be thinned if the container becomes crowded.Container Growing
Suitable for container growing
Minimum container size: 2 gallons