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Abstract Detail



Developmental and Structural Section

Carlquist, Sherwin [1], Schneider, Edward [2].

Origins and Nature of Vessels in Monocotyledons. 14. Vessellessness in Orontioideae (Araceae): Adaptation or Relictualism?

SEM studies of tracheary elements of subfamily Orontioideae (Lychiton, Orontium, Symplocarpus) of Araceae show unexpected features. The plants are entirely vesselless. There are small pores in pit membranes of end walls of tracheids in roots and stems, but pit membranes remain intact. End wall pit membranes of stems have a coarse fibrillar texture, somewhat reminiscent of (but different from) those of Nymphaeaceae and Cabombaceae. Acoraceae, which are also vesselless, represent the first branch of the monocot tree, according to phylogenies, and the orontioids form the next branch. Vessellessness is therefore a potentially plesiomorphic feature in monocots, but it may also be related to the highly mesic habitats of Acoraceae and the orontioids. Various other non-submersed monocots have vesselless or near-vesselless xylem. Sectioned xylem of Orontioideae is also very suggestive of stages in development of the pit membranes of both end walls and lateral walls of tracheids: open networks of cellulosic fibrils apparently precede the addition of denser fibrillar meshes, key information in assessing to what extent perforations in scalariform perforation plates of vascular plants may stop formation at the open network stage, and to what extent a thicker pit membrane experiences lysis and disintegration as the vessel element matures.

Broader Impacts:


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1 - Santa Barbara Botanic Garden, 1212 Mission Canyon Road, Santa Barbara, CA, 93105, USA
2 - University of Minnesota, Horticultural Sciences, Landscape Arboretum, 3675 Arboretum Drive, Chaska, MN, 55318, USA

Keywords:
monocot origins
skunk cabbages
vessel ontogeny
vessellessness
xylem ultrastructure.

Presentation Type: Oral Paper:Papers for Sections
Session: 15
Location: Jasperwood/Riverside Hilton
Date: Tuesday, July 30th, 2013
Time: 9:00 AM
Number: 15005
Abstract ID:72
Candidate for Awards:None


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