Psilotaceae

The family consists of two genera: Psilotum and Tmesipteris. Their natural range is primarily restricted to tropical and subtropical regions worldwide. They are typically found in humid environments where they grow as epiphytes on tree trunks or in rock crevices, which dictates their specific requirements when cultivated in man-made environments.

Botanically, the Psilotaceae are distinct because they lack true roots and true leaves. Instead, they rely on rhizoids associated with mycorrhizal fungi for water and nutrient absorption. Their stems undergo dichotomous branching and contain chlorophyll, meaning the green stems perform the primary photosynthetic activity for the plant, adapting them well to low-light understory conditions.

Agrotechnical requirements for these plants are rigorous. They demand high humidity, consistent tropical temperatures, and a porous, well-draining substrate. Because they depend on mycorrhizal associations, they do not thrive in highly fertilized commercial soils. Propagation is primarily achieved through spores, which requires a strictly controlled, sterile laboratory or greenhouse environment to succeed.

The primary use of these plants is for scientific research and display in botanical gardens. They are susceptible to typical greenhouse pests like scale insects and mealybugs, as well as root rot caused by stagnant water. Maintaining proper aeration and managing humidity levels is the most critical factor in preventing disease outbreaks and ensuring the health of these unique specimens.