Abstract Detail

Anatomy and Morphology

Edelman, Sara [1], Richards, J. [1].

Distribution of Vegetative Branching Types in the Palms (Arecaceae).

Vegetative branching is common in the palms (Arecaceae), creating a diversity of architectures, from the iconic solitary palms to the horticulturally-common clumping palms. Current branching terminology describing vegetative branching diversity, however, is not consistent and does not accurately describe the range of palm branching types. Branching is a developmental process that entails initiation of a new shoot, determination of that meristerm as vegetative or sexual, and subsequent outgrowth of that meristerm. Historically, vegetative branching types have been distinguished at all levels of this process. In this study, (1) vegetative branching types in the palms were identified and defined based on the first two stages in the process, and (2) the phylogenetic distribution of palm branching types was described. Vegetative branching terms were defined through a review of the literature, and branching types were described from these reviews and from field observations at Fairchild Tropical Botanic Garden and Montgomery Botanical Center, both in Coral Gables, FL. In total, 1903 species out of 2501 species in the family (76% species coverage) drawn from all 181 palm genera were included. Five vegetative branching types were found: lateral axillary branching, shoot apical division, false vivipary, abaxial branching and leaf-opposed branching. In addition, two combinations of branching types occurred: lateral axillary branching + shoot apical division and lateral axillary branching + false vivipary. To determine the most abundant branching type, the number of species with each branching type was counted. Ancestral branching was predicted using the most parsimonious approach in the Mesquite software package (Mesquite, Inc.). The distribution of branching types among palm subfamilies varied from subfamilies. Ceroxyloideae and Nypoideae were each characterized by a single branching type (lateral axillary and shoot apical division, respectively). Corphoideae exhibited two branching types: lateral axillary and shoot apical division. Arecoideae and Calamoideae both exhibited four branching types; lateral axillary, shoot apical division, false vivipary and abaxial in the Arecoideae and lateral axillary, shoot apical division, false vivipary, and leaf-opposed in the Calamoideae. Most species exhibited no vegetative branching type (1043 species, 55% of observed species). Lateral axillary was the most common branching type, described in 646 species (34% of observed species). Lateral axillary branching and shoot apical division were identified as the earliest-evolved branching types. This study suggests that branching types have different evolutionary histories in the Arecaceae, and it is likely that the solitary habit is more common now than when palms initially diverged from commelinid relatives.

1 - Florida International University, Department of Biological Sciences, 11200 SW 8th Street, Miami, FL, 33199, USA

Keywords:
none specified

Presentation Type: Oral Paper
Session: 20, Anatomy and Morphology
Location: Fort Worth Ballroom 7/Omni Hotel
Date: Tuesday, June 27th, 2017
Time: 9:15 AM
Number: 20006
Abstract ID:197
Candidate for Awards:None