Spanish moss is a slender epiphytic perennial, which hangs in festoons up to 30 m long. However, the apparent length of the plants is due to numerous shorter individual plants, usually 15 to 25 cm long, which overlap each other. Only about 45 cm of a 3 m strand may actually be alive. The plant grows in a zigzagging pattern, and tangles around itself and its support. The leaves are small (up to 4.5 cm long) and narrow (up to 0.2 cm wide), linear, often twisted and contorted and densely covered with a thick layer of trichomes (scales), which gives it a silvery-grey appearance. The leaves are bright green when wet.
It flowers in the summer, often abundantly, although the tiny, pale yellow-green to blue, solitary flowers are inconspicuous. The flowers last about four days and have a pleasant, subtle fragrance, which attracts a variety of insect pollinators.
Spanish moss possesses striking adaptations to its environment. The entire surface of the shoot is covered with highly specialised trichomes (scales) which absorb water and nutrients from the atmosphere; they also reduce transpiration and reflect strong light. Tillandsia usneoides prefers moist habitats and is often abundant near rivers, ponds and lakes. During long periods of drought it becomes dormant. It can survive two months without rainfall but will die within three to four months of drought.
The plant is often grown as an ornamental plant in tropical areas.