Tillandsia usneoides (Spanish moss)
Spanish moss is a superb 'air plant' which grows in silverish festoons up to 30 m long, hanging from tree limbs, cliffs and even telephone wires.
Tillandsia usneoides seeds (Image: Marcelo Sellaro)
Rated by the UCN as of Least Concern (LC).
Found in a very wide range of subtropical and tropical habitats (mangroves, scrub, rainforest, gallery forest, montane forest, cloud forest), from 0 to 3300 m above sea level. Often abundant in wet habitats: along ponds, streams, rivers, and in swamps.
Bioindicators for air quality, fibres, garden mulch, livestock feed, binding agent, kindling, medicine, herbal remedies.
About this species
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. It can survive well in dry habitats too, through Crassulacean acid metabolism (CAM), a specialised way to photosynthesise. It can survive two months without rainfall but will die within three to four months of drought. In dark forest it hangs suspended from the higher limbs of trees (most commonly on trees that are dead). T. usneoides grows on a wide range of trees, both wild and cultivated, which have a high rate of mineral leaching. It does not appear to favour any hosts. Many tropical trees, however, release chemicals making conditions unfavourable for the growth of Spanish moss.
Geography and distribution
Tillandsia usneoides is the most widely distributed member of the Bromeliaceae family, occurring throughout tropical and subtropical America. It is found in the southeastern United States as far north as coastal Virginia, and throughout Mexico, the West Indies, Central and South America, as far south as Argentina and Chile.
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.
Tillandsia usneoides reproduces both sexually and vegetatively. 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. Any self-pollinated flowers fail to produce seeds. The fruits are tiny, cylindrical capsules, which split and release the seeds the following winter. Seed dispersal is aided by delicate hairs, 1 to 2 cm long, which act as a parachute. These hairs are covered with tiny barbs, which anchor in the cracks of rough bark or other sites.
Seedlings have root-like holdfasts, which soon dry up as the plant develops; mature plants have no roots. Vegetative reproduction and spread is much more common than propagation by seeds. Small broken plant fragments are scattered by wind, birds and animals and can also float. They grow into new plants if they land on appropriate sites, and T. usneoides may owe its unusually extensive range largely to powerful hurricane winds.
Threats and conservation
Tillandsia usneoides is the most widespread of all bromeliads, having an essentially continuous latitudinal range of over 8000 km. It is one of the most abundant members of the Bromeliaceae family and locally common throughout its range. Some populations have declined due to high rates of deforestation and over-collection. Because of its very wide distribution, abundance and adaptation to a very broad range of habitats and climates, this bromeliad is not threatened and there are no specific conservation measures needed.
Epiphytic plants such as Tillandsia usneoides are very useful as bioindicators for air quality. Since these plants obtain all their nutrients and water from the air, their tissues contain nearly the same levels of elements, including pollutants, as the atmosphere they grow in. Research has shown that T. usneoides is a particularly reliable indicator of metal pollutants in the air.
T. usneoides yields a tough, elastic fibre from the non-living vascular tissues of the stem. This fibre resembles black horse hair and was once of major economic importance. To obtain the fibre, festoons of the plants were harvested from trees using long poles (up to a tonne from one tree) and "cured" by burying the plant material in pits or trenches until the living, greenish tissues decayed and only the black vascular tissues remained.
The resulting fibre was used as stuffing material for upholstery in furniture, cars and mattresses; it was also used in ropes and floor mats. Manufacturers in Liverpool were using Spanish moss imported from America as mattress filling in the 1840s. It has now been largely replaced with synthetic fibre, but T. usneoides is occasionally used in arts and crafts, in upholstery and insulation. It is a popular garden mulch and is used in the florist industry to hold moisture at the base of flower arrangements. It is also used throughout Latin America as a Christmas ornament.
Native American tribes used T. usneoides for livestock feed, as a binding agent in clay bricks and plaster, and for kindling. Women wove the fibre into the fabric of their dresses. It was used in medicine for a range of purposes, and has many uses in contemporary herbal medicine in Latin America. For example, preparations of the plant are used on haemorrhoids, abscesses and tumours, and are taken orally for heart, liver and lung ailments. Research has shown that T. usneoides has antiviral, anti-inflammatory, and analgesic activities, among others, that may support its use in herbal remedies.
Spanish moss is rarely cultivated, despite it being easy to do so. The plant is available from specialised nurseries and can be hung in greenhouses or on patios.
Marcelo Sellaro, who works in the moist tropics section at Kew, notes that this species requires constant misting so as to be able to absorb water and mineral salts from the air through the scales on its surface. Good air circulation should be maintained around the plant, and a high light intensity is beneficial. The nursery zone in which the species is grown is kept at temperatures between 15 and 35 ˚C. The plants are suspended from hanging structures with no soil required at all. It is thought that the species can tolerate temperatures close to freezing for a few days at a time.
Where to find Spanish moss at Kew
Epiphytic ferns, bromeliads and orchids can be seen in the wet tropical zones of the Princess of Wales Conservatory with examples of Tillandsia in the cloudforest zone.
Tillandsia usneoides can also be seen hanging from other plants in the Palm House.
Arny, N.P. (1996) Spanish Moss and Ball Moss. University of Florida Cooperative Extension Service, Institute of Food and Agricultural Services.
Bennett, B.C. (1986) The Florida Bromeliads: Tillandsia usneoides. Journal of the Bromeliad Society 36 (4):149-151.
Benzing, D.H. (2000) Bromeliaceae, Profile of an Adaptive Radiation. Cambridge University Press, Cambridge, UK.
Billings, F.H. (1904) A Study of Tillandsia usneoides. Botanical Gazette, 38 (2): 99-121.
Duke, J.A. (2009). Duke's Handbook of Medicinal Plants of Latin America. CRC Press, Boca Raton.
Figueiredo, A.M.G., Alcalá, A.L., Ticianelli, R.B., Domingos, M. & Saiki, M. (2004). The use of Tillandsia usneoides L. as bioindicator of air pollution in São Paulo, Brazil. Journal of Radioanalytical and Nuclear Chemistry 259: 59-63.
Filho, J. A. S. and E. M. C. Leme. (2007) Fragments of the Atlantic Forest of Northeast Brazil: Biodiversity, Conservation and the Bromeliads. Andrea Jakobson Estudio, Rio de Janeiro.
Garth, R. E. (1964) The Ecology of Spanish Moss (Tillandsia usneoides): Its Growth and Distribution. Ecology 45: 470-481.
Krulik, J. 2008. Varieties of Spanish Moss. Journal of the Bromeliad Society. 58: 241-288.
Kew Science Editor: Florence Romand-Monnier
Kew contributors: Sustainable Uses Group, HPE, Marcelo Sellaro
Copyediting: Emma Tredwell
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