Neither a moss or a fungus, Spanish moss (Tillandsia usneoides) is a bromeliad with thin, dangling thread-like leaves that reach up to 10 feet in stringy length. Native from the southeastern United States across the West Indies, Central America and as far south as Chile and northern Argentina, it is perhaps the most famous bromeliad in the world after the pineapple. It is an epiphyte, a plant that grows upon another plant, naturally draping the limbs of trees.
Spanish moss has the greatest natural range of any bromeliad in the world, as noted by Robert Lee Riffle, noted tropical plantsmen from Florida. It occurs in the coastal southeastern United States from Virginia to Florida and westward to Texas. In Latin America its range continues from the Rio Grande through Central America and the West Indies, southward into lowland and warm highlands across South America to northern Chile and Argentina.
Lacking roots, Spanish moss needs a warm growing season with light frosts in winter at most and lots of ambient humidity and drenching rainfall. Its foliage is silvery, with scale-like trichomes, that protect the thread-like foliage from excessive sunlight and dryness. Thus, it grows in bright, indirect shade to partially sunny locations, where it is exposed to no more than four to six hours or direct sunlight in the heat of summer. Good air circulation around the draping foliage prevents fungal rot in the warm, moist, humid growing conditions.
Found extensively in evergreen tropical trees and winter-deciduous tropical trees, massive curtains of Spanish moss foliage prosper in the dappled sunlight under tree leaves. Although tolerant of occasional exposure to hot, baking summer sunshine, the foliage is lush and nearly succulent especially when humidity is high. It is commonly associated with the live oak and bald cypress trees in the American South and in tropical America nearly any tall evergreen tree, especially in the upper limbs where wind, bright light and exposure to rain is prevalent.
If humidity is high year round, Spanish moss also can germinate and clasp onto rock surfaces on cliffs, cave openings or moist escarpments. This ability to sprout and dangle from any advantageous coarse surface manifests itself in human settlements, where the bromeliad sprouts up and grows on roof eaves, telephone lines or fences.
Plant Life Cycle
The small seed of Spanish moss is scattered by wind or dripping water and is wedged into cracks and crevices on tree bark, crotches of plant branches and twigs, or in humusy nooks between rocks or on the decaying wood of fallen trees. Warmth and humidity causes the seed to sprout and grow curling, eyelash-like leaves that elongate and grow to form long strings. Usually growing from two to 10 feet in length, healthy plants in perfect conditions can grow as long as 50 to 100 feet, albeit rare. In summer, when humidity is high and seasonal rains common, small chartreuse flowers appear almost invisibly on the thread-like leaves and are pollinated in the wind. Seeds ripen and again scatter, germinating only in optimal locations and conditions.
Spanish moss will live for decades. As wind or sheer weight of the foliage breaks off and falls onto lower tree branches or to the ground, new growth continues on the plant. Only lack of humidity and rainfall or intense, baking sunlight will slowly degrade the bromeliad and kill it once all foliage is fully dehydrated. Plants floating in water will also die.
Prosperous in frost-free tropical settings, Spanish moss tolerates light frosts and short bouts with subfreezing temperatures. Clumps protected under the evergreen foliage of trees in winter are most likely to survive frosts and light freezes than those exposed on upper branches or on bare deciduous trees. It is winter hardy in USDA Hardiness Zones 7 and warmer. Spanish moss native to areas that are warm and humid year round, such as the jungles of equatorial America usually have slightly wider foliage and lack tolerance to chilly temperatures compared to plants native to tropical highlands or the American Southeast.