Tillandsia usneoides (commonly called Spanish moss, although it is neither Spanish nor moss) is an atypical angiosperm, a primitive and xerophytic member of the Bromeliaceae. It is native to the coastal plain of the United States from Virginia to Texas and to tropical America as far south as Argentina and Chile. Its distribution may be correlated with major storm paths (Garth 1964). The blue-gray plant consists of a slender stem, up to 25 feet long, with alternating leaves growing chain-like to produce “festoons” (Billings 1904). The leaves are needle-shaped and covered with silver-gray scales. The inconspicuous fragrant flowers, which appear from April to June, are blue or pale green and have three petals. Spanish moss is dependent upon a host species or object upon which to grow. It is typically found on the branches of sparsely foliated or dead deciduous trees in high-humidity environments with soils rich in calcium carbonate (Garth 1964).
Spanish moss can grow from seeds but is typically spread by windblown fragments or from fragments incorporated in birds’ nests. This epiphyte has no roots; it captures all its water and nutrients from rain and dust in the atmosphere. Its vascular system is degenerate: Spanish moss has no functional xylem or phloem, water is absorbed by scales over the entire surface of the plant and every cell of the plant either photosynthesizes on its own or is proximal to a cell that shares resources (Billings 1904). It fixes carbon by Crassulacean acid metabolism (CAM), an adaptation to arid conditions in which carbon dioxide enters the stomata at night to reduce loss of water in its cells.
Native American tribes traditionally used fibers derived from Spanish moss to weave into coarse cloth for bedding, to cord into rope, and to produce fire-tempered pottery (USDA NRCS 2013). Because the plant accumulates heavy metals, including mercury, it has proven useful in monitoring mercury pollution in urban areas (Malm et al. 1998; Fonesca et al. 2007).
