Carbon and water balance

Temperate zone ora dominate the early literature on plant ecophysiology, but Bromeliaceae account for a disproportionate number of the tropical species studied during this period. Billings (1904) recorded moisture exchange during his inquiry on the biology of Spanish moss. Mez (1904) and several European contemporaries demonstrated how the foliar tri-chome of this same epiphyte and comparable Tillandsioideae eliminates need for absorptive roots. Harris (1918) contrasted osmotic pressures in the leaves of trees and associated bromeliads and co-occurring vascular epiphytes in Florida and Jamaica.

Wherry and Capen (1928) surveyed Tillandsia usneoides growing along Florida highways for its capacity to accumulate nutrients and certain technological metals. Research on pineapple metabolism began in earnest during the late 1930s. Finally, Leopoldo M. Coutinho included numerous Bromelioideae and Tillandsioideae in his pioneering investigations on the pathways responsible for CO2 assimilation by diverse Brazilian ora (e.g., Coutinho 1963). Since then, a growing number of scientists have been measuring gas exchange, chlorophyll uorescence and other indicators of plant performance and physiological state to expand the database on Bromeliaceae.

Current records of carbon xation pathways, many accompanied by data on water balance and light relations, document the ecostrategies of more bromeliads than of members of any other family (Martin 1994; Table 4.1). Moreover, concerns about issues ranging from global change to drought-tolerance assure continuing interest in the ecology and evolution of Bromeliaceae. Ananas comosus, Aechmea magdalenae, Bromelia humilis, Tillandsia usneoides and Guzmania monostachia constitute the best-known species; less complete pro les of many more taxa further attest to the exceptional variety of growing conditions these plants experience in situ.

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