Abstract Detail


McMurchie, Elizabeth [1], Crock, Josephine [1], Clark, Lynn [2].

From leaves to lemmas: Examining patterns in floral bract macro- and micromorphology in Guadua (Poaceae: Bambusoideae: Bambuseae).

In foliage leaf blades of the Neotropical woody bamboo genus Guadua, subtribe Guaduinae, the presence of certain micromorphological features, including broad, often ridged silica bodies in costal zones, is typically associated with species found in savanna habitats. Abundant papillae on foliage leaf blades are also associated with several savanna species of Guadua, which are notable for sharing several macromorphological features uncommon in forest-associated species of Guadua, including relatively short and narrow culms, culm leaves with subequal sheath and blade, narrow foliage leaves, and short pseudospikelets. The foliage leaf micromorphology of savanna-associated Guadua species and that of forest-associated Guadua species differ significantly from each other. However, even the most basic questions about micromorphology of Guadua lemmas and paleas (the two bracts enclosing each flower), such as whether there are species-specific micromorphological differences associated with these floral parts, are currently unanswered. As many Guadua herbarium specimens include only partial sets of material, in some cases completely lacking vegetative parts such as foliage and culm leaves, micromorphology of lemmas and paleas could potentially serve as a tool to help differentiate between species with otherwise similar fertile morphology. In this study, we sought to address whether there are species-specific differences in Guadua lemma and palea micromorphology and, if such differences exist, whether they follow similar habitat- or habit-based patterns as in Guadua foliage leaf micromorphology. By reviewing images of lemmas and paleas taken with scanning electron microscopy (SEM), we constructed a multivariate, binary dataset recording the presence or absence of different micromorphological features on individual Guadua specimens. Additionally, we considered differences in aspects of palea morphology, such as length of wings on the keels and length of cilia, which appear to vary at the species level. From the micromorphological presence and absence data, we obtained a distance matrix using the simple matching coefficient and visualized our data using principal coordinates analysis (PCoA). We visualized our palea macromorphological data using a similar PCoA based on Euclidean distances. To determine whether there were significant differences in the floral bract macro- and micromorphology of Guadua based on habitat, habit, and region, we ran factorial multivariate analyses of variance (MANOVA) using the RRPP package in R (randomized residuals in a permutation procedure) and conducted model comparison using likelihood ratio tests. Our preliminary results indicate that Guadua lemma and palea micromorphology does differ between species and exhibits patterns based on habit and habitat that roughly mirror those of foliage leaves of the same species. Palea macromorphological features also appear to follow habit- and habitat-related patterns seen in species-level variation in micromorphology.

1 - Iowa State University, Department of Ecology, Evolution, and Organismal Biology, 251 Bessey Hall, 2200 Osborn Drive, Ames, IA, 50011-4009, USA
2 - Iowa State University, Department Of Ecology, Evolution, And Organismal Biology, 251 Bessey Hall, 2200 Osborn Dr., Ames, IA, 50011, United States


Presentation Type: Oral Paper
Number: SYST I004
Abstract ID:580
Candidate for Awards:None

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