Foliage leaf and floral bract micromorphology vary by habitat and habit in Guadua (Poaceae: Bambusoideae: Bambuseae)

Abstract

Micromorphology of bamboo foliage leaves is a valuable tool for determining taxonomic placement of species. Members of the Neotropical woody bamboo subtribe Guaduinae, including Guadua, are unusual in that most have stomata on both leaf surfaces. Foliage leaves of savanna-dwelling Guadua also often feature papillae on both surfaces, while the plants share a suite of macromorphological characteristics. We sought to evaluate statistically whether there were patterns in micromorphological variation in Guadua foliage leaves that aligned with known habitat- or habit-based patterns in macromorphological variation. Additionally, we investigated the micromorphology of Guadua floral bracts to determine whether they displayed variation similar to that of foliage leaves. By analyzing scanning electron microscopy images of these structures, we constructed binary datasets recording presence or absence of micromorphological features on foliage leaves and floral bracts of Guadua specimens belonging to 28 and 24 described species, respectively, as well as four and two putative species, respectively, for foliage leaves and floral bracts. We produced distance matrices using simple matching coefficient for the micromorphology datasets, visualized our data using principal coordinates analysis, and determined whether there were significant differences in foliage leaf and floral bract micromorphology based on habitat and habit using factorial multivariate analyses of variance. Our results indicate that Guadua foliage leaf and floral bract micromorphology differs significantly between Guadua found in savanna, forest, or river habitats and between Guadua of small arching, climbing, or larger erect habits.