Abstract Detail

Anatomy and Morphology

The Structure of the inflorescence in the Lowiaceae (Zingiberales) has similarities to that of the Strelitziaceae that may support common ancestry.

The inflorescence of the monotypic Lowiaceae (Orchidantha) may hold a key to unraveling the phylogenetic placement of the families Musaceae, Heliconiaceae, Strelitziaceae, and Lowiaceae. After nine phylogenetic studies the (Lowiaceae, Strelitziaceae) is the only stable clade that has emerged in this half of the order Zingiberales. The inflorescence consists of two lateral branches (two enriching branches, or paracladia) and lacks a main axis (a main florescence) that extends beyond these branches. Each branch bears four bracts and a single flower, before aborting. The first bract is a sterile prophyll. The second and third bracts bear higher order branches (enriching branches). The fourth bract subtends a flower, the only flower of the highly reduced flower cluster (coflorescence) that characterizes the genus. In technical terms Orchidantha has a polytelic synflorescence that lacks a main florescence. That is, it has a truncated polytelic synflorescence and bears solitary flowers in coflorescences on determinate enriching branches. Many of these features are shared with the Strelitziaceae. The Strelitziaceae is the only other family in the Zingiberales where the polytelic synflorescence lacks a main florescence. Of the three genera in the family, both Ravenala (one species) and Strelitzia (five species) lack a main florescence. Flowers are produced on lateral enriching branches that terminate in coflorescences (thyrses). Unlike the Lowiaceae, the main inflorescence axis of these plants continues to grow and produce leaves. In the other two species of Strelitzia (S. reginae, S. juncea) the coflorescences are further reduced to a single bract that subtends a lateral cincinnus. The inflorescence of Phenakospermum (one species) consists of a single main florescence with no enriching branches or coflorescences. This inflorescence structure is likely uniquely derived within the family. Other characters that unite the Lowiaceae and Strelitziaceae are the presence of a long prolongation of the ovary, and a delay in the formation of the third sepal during flower development, a character that is also shared with the Musaceae. Inflorescence and flower structure is now well established in this small, but important family.

1 - Univ Of NC Greensboro, Department Of Biology, Po Box 26170, Greensboro, NC, 27402, United States

Keywords:
development
flower
inflorescence
Lowiaceae
Strelitziaceae
Orchidantha
phylogeny
flower development
inflorescence development.

Presentation Type: Oral Paper
Session: AM1, Anatomy and Morphology
Location: Virtual/Virtual
Date: Wednesday, July 29th, 2020
Time: 11:30 AM
Number: AM1007
Abstract ID:167
Candidate for Awards:None