Foliar Trichomes & Evaluation of Taxonomic Affinities in the Bromeliaceae by JOHN F. UTLEY in J Brom. Soc. 29(5): 208-11. 1979
One of the greatest difficulties facing anyone interested in the Bromeliaceae is the identification of sterile material. Even when flowering or fruiting material is available, an unequivocal designation of genus is not always possible due to the evanescent nature of the floral features which are critical in defining many genera. This situation is frequently aggravated by the deceptive vegetative similarity of many species from different genera. A good, but by no means unique, example of the problems which have arisen due to the recondite nature of critical generic characters is Guzmania spectabilis (Mez & Werckle) Utley. This species was originally described as Thecophyllum spectabile Mez & Werckle in 1904 on the basis of a rather battered and incomplete specimen collected in Costa Rica. When Smith and Pittendrigh dismembered Thecophyllum in 1953, they transferred this species to Vriesea; its name thus became Vriesea spectabilis (Mez & Werckle) L. B. Smith & Pittendrigh. My recent collections from Costa Rica have shown that this species has the floral characteristics of Guzmania and, as a consequence, the taxon was recently transferred to that genus (Utley, 1978a). In addition to the fused sepals and petals found in Guzmania, the foliar trichomes of G. spectabilis are most similar to those of its putative allies in Guzmania and unlike those of the thecophylloid vrieseas, its former neighbors in Vriesea. As can be seen in Figs. 2A and 2B, G. spectabilis and G. squarrosa (Mez & Sodiro) L. B. Smith & Pittendrigh have strikingly similar trichomes. The differences between the trichomes of these two species and the range of trichome morphologies encountered in the thecophylloid vrieseas (those vrieseas which were, or would have been, in Thecophyllum) are equally striking (cf Fig. 2A, 2B, 2C and 2D). This situation illustrates the potential usefulness of foliar trichomes as taxonomic characters.
As part of a systematic revision of the thecophylloid vrieseas, I recently completed an extensive study of the trichomes of these unique vrieseas (Utley, 1978b). Thus far, my research indicates that, while these structures are not a panacea, they are often useful in delimitation or evaluation of taxa. What are needed now are not broad scope surveys of a potpourri of taxa, but systematic examinations of foliar trichomes from groups of related species. Furthermore, the variability of trichome structure within taxa, as well as the influence of environmental parameters on trichome morphology must be determined whenever possible. These studies are a necessary prerequisite to an effective utilization of foliar trichomes in bromeliad classification.
A NEW COMBINATION IN GUZMANIA (BROMELIACEAE) by John F. Utley, Department of Botany Smithsonian Institution Washington, D.C. Phytologia 40: 55-7. 1978
When Thecophyllum spectabile Mez & Werckle was described in1904, Mez noted that the relationships of this species seemed to be with several Andean and Antillian taxa rather than with other Costa Rican Thecophyllums. Smith and Pittendrigh dismembered Thecophyllum in 1953 and transferred a single species to Tillandsia, several to Guzmania and the majority, including Thecophyllum spectabile, to Vriesea. At that time Thecophyllum spectabile was known only from the type collection which lacked complete floral material."Flores ob speciminis statum putridum ignoti" (Mez, 1904). Recent flowering collections of the taxon have shown that the species has fused sepals and petals {Fig. 1}. These character states are discordant within Vriesea and necessitate the transfer of the species to the genus Guzmania.
Guzmania spectabilis is phenetically most similar to a complex of former thecophyllums which is centered in the northern and central Andes. In addition to differences in floral characters, the foliar trichome morphology of G. spectabilis is inconsistent with that of the thecophylloid vrieseas but is in close agreement with that of its apparent allies in Guzmania [e.g., Guzmania squarrosa (Mez & Sodiro) L.B. Smith Pitt.]. —SeeSmith & Downs 1977
