Air Plants (Cornell, 2012), by David H. Benzing, explores the properties of a unique and hardy group of plants. Benzing, a Professor of Biology at Oberlin College, dives into the scientific classifications, anatomical and physiological structures, and environmental requirements that allow air plants to adapt and thrive. This excerpt focuses in on how air plants are used by humans.
Epiphytes figure prominently in ornamental horticulture, but except for the hemi-epiphytic orchid Vanilla planifolia and a couple of large-fruited cacti (“dragon fruits,” genus Hylocereus) that grow the same way, none provide food, fiber, or chemicals in commercial quantities. Additional species yield mi- nor fruits for local markets and likely will not gain greater attention without further domestication (e.g., several members of the mulberry-like genus Coussapoa). Perhaps some currently obscure drupe or berry produced by an epiphyte will emerge as yet another miracle source of health-promoting agents from the tropical rain forest! The practice of harvesting Spanish moss to stuff upholstery gave way long ago to use of synthetic alternatives. More modest applications continue, such as its use for lining flowerpots and Easter baskets.
Easily met requirements for growth, appropriate dimensions for container and landscape culture, and often-colorful foliage, floral bracts, and flowers ac- count for the immense popularity of many of the epiphytes in developed countries. Likewise, many a rural house and garden across the tropics features transplants from nearby woodlands. Christmas celebrations and other religious ceremonies consume countless epiphytes, mostly bromeliads, in many parts of Latin America. Similar choices commonly decorate household shrines and roadside sites of fatal accidents. Individuals in places like southern Mexico are being encouraged to reduce pressures on wild populations of bromeliads by propagating endangered species in private woodlots.
Many of the most valuable of the cultivated cacti, philodendrons, gesneriads, and orchids have epiphytic origins like those of the ornamental bromeliads, and markets for their kind continue to expand in the developed world. Guatemala and Mexico exported some 72 million bromeliad plants as far back as 1989, mostly to Western Europe, Japan, and North America. High dollar value is second only to habitat destruction as a threat to the wild populations of numerous species of bromeliads, cacti, and orchids.
The epiphytes warrant closer scrutiny as potential sources of therapeutics in addition to use as ornamental cultigens. About 15% of the 670 medicinal plants employed by the Shuar Indians of Ecuador, for example, grow above ground, according to one authority. Herbaceous vines and lianas outnumber the epiphytes, largely because so many belong to the pharmacologically well-endowed families Apocynaceae, Bignoniaceae, Convolvulaceae, and Fabaceae. Araceae, Bromeliaceae, Gesneriaceae, and Orchidaceae account for the largest numbers of epiphytes listed, many for other than medical utility. Exceptions include numerous Gesneriaceae, especially several of the epiphytes characterized by red- pigmented leaves that suggest efficacy for gynecological problems.