Centropogon (Campanulaceae: Lobelioideae) includes 216 species distributed from Mexico and the Lesser Antilles to Bolivia and Brazil. The genus is characterized by solitary axillary flowers or racemose terminal inflorescences, entire corolla tube, occluded anther orifice, baccate fruit, and ellipsoidal seeds twice as long as broad or less. Five sections are currently recognized Centropogon, Siphocampyloides Benth., Wimmeriopsis McVaugh, Burmeisteroides Gleason, and Niveopsis Lammers. The section Siphocampyloides, comprising 98 species, is distinguished by the possession of branched (i.e., arbusculiform) trichomes. However, other characteristics, such as floral features, suggest this may not be the optimum classification. The species of subsection Peruviani McVaugh resemble section Burmeisteroides in corolla morphology, while those of subsection Brevilimbati McVaugh resemble section Wimmeriopsis. Furthermore, branched trichomes occur infrequently in three other genera: Neotropical Burmeistera and Siphocampylus and Hawaiian Cyanea. Examination of trichome morphology via scanning electron microscopy reveals considerable variation among numerous species. Some trichomes are stalked while others are sessile. Trichome branching patterns observed include dendritic, stalked-multangulate, and dendritic-echinoid. Other variation that is observable includes distance between branches, total trichome length, and total coverage of indumentum over the surface of the leaf. Preliminary evaluation of the data suggests some correlation between trichome type and other characteristics (e.g., floral features) traditionally used in the classification of the genus.

Key words: Campanulaceae, Centropogon, Lobelioideae, trichomes