Decombeix, Anne-Laure , Taylor, Edith L. , Taylor, Thomas N. .
Sprouting in fossil gymnosperms: evidence from the Permian and Triassic of Antarctica.
Sprouting from the trunk and branches (epicormic sprouts), from the collar zone (basal sprouts) or from the roots (root suckers) is common in extant trees, principally among angiosperms. While sprouting has important implications in terms of vegetative regeneration and reproduction, it is rarely documented in fossil plants and, as a consequence, the long term evolution of this functional trait remains poorly known. We describe gymnosperm axes from the Permian and Triassic of Antarctica that document the occurrence of several types of sprouting behavior in fossil trees from high latitude environments. Two small trunks collected in Late Permian permineralized peat from Skaar Ridge, Central Transantarctic Mountains, display clusters of epicormic sprouts. Each is composed of about 50 young shoots 0.7-3 mm wide. Evidence from wood and shoot anatomy suggests that these trunks probably belonged to the glossopteridalean seed ferns that dominated the floras of Gondwana during the Permian. At the same locality, some young axes of Vertebraria, the root system of the glossopterids, produce unusual laterals that are distinct from typical Vertebraria and from other types of roots reported from this site. They have a stem-like anatomy, with a circular to pentagonal parenchymatous pith surrounded by a small amount of secondary xylem. These lateral axes are interpreted as evidence of the production of root suckers in Vertebraria. At the Middle Triassic locality of Fremouw Peak, large anatomically preserved axes representing roots and basal portions of the conifer Notophytum show clusters of small adventitious traces extending to the periphery of the axis. These clusters are composed of young stems, sometimes associated with root traces, and are interpreted as evidence of root and/or basal sprouting in Notophytum. The implications of the Permian and Triassic Antarctic plants are discussed in the context of the ecology of high-latitude tree growth, as well as in the broader perspective of the evolution of sprouting in gymnosperms.
Log in to add this item to your schedule
1 - University of Kansas, Department of Ecology & Evolutionary Biology, Natural History Museum and Biodiversity Research Center, 1200 Sunnyside Avenue, Lawrence, Kansas, 66045-7534, USA
Presentation Type: Oral Paper:Papers for Sections
Location: 555B/Convention Center
Date: Monday, August 2nd, 2010
Time: 3:00 PM