Elisens, Wayne .
Seed morphology and its phylogenetic significance in the Gratioleae (Plantaginaceae).
Seeds representing 42 species placed in 9 genera of the Gratioleae were examined for variation in seed surface sculpturing to identify useful characters, test hypotheses of generic relationships, and elucidate seed character evolution in a phylogenetic context. Seed coat patterns are broadly categorized into crested (Leucospora), sulcate (Stemodia p.p.), or reticulate seeds. Examination of anticlinal wall relative height and ornamentation of anticlinal and periclinal walls resulted in the delineation of 16 seed types. Anticlinal walls exhibited high or low relief and have either smooth, mammilate, or nodulate ornamentation. Periclinal wall ornamentation is the most variable character in the tribe and seeds exhibit smooth, alveolate, papillate, verrucate, rugulate, corrugate, or nodulate surfaces. Reticulate and crested seeds have surface topographies resulting from differential elongation and collapse of epidermal cells, whereas sulcate seeds result from collapse of epidermal and hypodermal cells. Most genera have unique seed types and larger genera with more sampled species encompass three (Mecardonia) to five (Bacopa, Stemodia) seed types. Mapping of seed characters onto a tribal molecular phylogeny indicates the evolution of sulcate seeds within a broader lineage of reticulate seeds and supports hypotheses of the polyphyly of the genus Stemodia with lineages characterized by either reticulate or sulcate seeds.
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1 - University of Oklahoma, Botany & Microbiology, 770 Van Vleet Oval, Norman, OK, 73019, USA
Presentation Type: Oral Paper:Papers for Sections
Location: 555A/Convention Center
Date: Wednesday, August 4th, 2010
Time: 8:45 AM