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Awn morphology influences dispersal, microsite selection and burial of Australian native grass diaspores

journal contribution
posted on 2021-01-11, 00:48 authored by Annette M Cavanagh, John MorganJohn Morgan, RC Godfree
© Copyright © 2020 Cavanagh, Morgan and Godfree. Seed dispersal is a vital part of a plant’s life cycle that enables progeny to reach new sites suitable for burial and establishment. Awns are characteristic of many grass species and enable diaspores to self-disperse. Little is known, however, about the role of different awn morphologies in dispersal or burial. The objective of this study was to investigate the influence of awn morphology on diaspore surface dispersal and burial among representative Australian Poaceae. Surface dispersal, burial and microsite selectivity of diaspores were compared across 30 grass species and ten awn morphological types using laboratory and natural simulation experiments. The presence of an awn significantly facilitated surface dispersal and burial of diaspores, with awn length and hygroscopic activity being positively related to both surface dispersal and burial depth. Geniculate (once-bent) and bigeniculate (twice-bent) awns were the most efficient at surface dispersal. Burial efficiency, however, was influenced by microsite conditions; a surface obstruction increased burial for almost all awn types, while falcate (curved)-awned species were effective at burying without such objects. This study indicates that awn morphologies likely play different functional roles in the success of Australian grass progeny.


The Friends of Grasslands, ACT, provided financial support (Grant reference: FSP2017-03). Sarah Mathews instigated the method for quantifying diaspore movement. Warren Paul provided assistance with data analyses. Andre Messina (Royal Botanic Gardens Victoria), Scott Tunbridge (La Trobe Wildlife Sanctuary), Simon Heyes, Zac Walker and Brendan Lepschi provided seed for experiments. Nick Moore provided technical assistance.


Publication Date



Frontiers in Ecology and Evolution



Article Number



13p. (p. 1-13)


Frontiers Research Foundation



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