Fragrances

Anecdotes about the qualities of oral fragrances among the bromeliads abound, but few of these publications (e.g., Hegnauer 1963, 1986; Chapter 13) include chemical determinations. Adjectives that range from sweet and pleasant (triterpenes such as citronellol, geraniol and nerol in some tillansdias; Hegnauer 1963) to musty, garlic-like, greasy, bituminous, as in coal gas, and reminiscent of spoiled cabbage indicate varied chemistry and diverse targets. Associations with speci c ower form, color and timing indicate two groups of chemicals, one attractive to the common insect pollinators and the other to bats.

Closely allied lineages tend to produce similar odors (e.g., Tillandsia, particularly subgenera Anoplophytum, Diaphoranthema and Phytarrhiza, and Catopsis sweet-smelling and Vriesea section Xiphion unpleasant types). Lures may be convergent with those produced by other taxa. Knudsen and Tollsten (1995) reported reliance on the same and related S-containing compounds by bat-serviced owers representing six families (no Bromeliaceae). Odors that attract prey to Brocchinia reducta shoots belong to the rst category (Chapter 5).

Timing also distinguishes the fragrant- owered bromeliads. Chiropterophilous types smell strongest at dusk or later during the night. Quite a few sweet-scented species do the same, or their emissions peak after sundown following more modest activity that day. Pale corollas, sometimes with mbriate margins (T xiphioides; Fig. 3.3F), probably indicate moth pollination. Till (1992a) reported that several species of Tillandsia subgenus Diaphoranthema (e.g., T. aizoides, T. virescens) developed strong fragrances at about dawn, became odorless between about 10.00 and 17.00 hours, and then resumed advertisement through the night after which the corolla withered. Sazima et al. (1989) reported only a faint scent from the in orescences of Encholirium glaziovii, which otherwise is well equipped for bat pollination. Knudsen and Tollsten (1995) interpreted this de ciency as evidence of derivation from ornithophilous stock. If true, one oral character changed less than several others as ancestors abandoned one group of vertebrates for another.

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