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Abstract Detail



Ecological Section

Koontz, Stephanie M. [1], Weekley, Carl W. [1], Haller Crate, Sarah J. [1], Menges, Eric S. [2].

Patterns of chasmogamy and cleistogamy by age and season in a rare Polygala.

Cleistogamy in angiosperms historically has been undocumented and understudied. With the exception of a few genera, little is known about when and why species express cleistogamy, its reproductive contribution and the fitness consequences of producing both selfed and outcrossed progeny. The endangered perennial Polygala lewtonii (Polygalaceae) exhibits both aerial and subterranean cleistogamy (CL) as well as chasmogamy (CH), on the same plant. Monthly from March 2008 to December 2012, we monitored patterns of the three floral types on individual plants in a protected longleaf pine/wiregrass Florida sandhill ecosystem. We followed plants from germination to senescence and recorded the number of CH flowering stems, fruits from aerial CL flowers and subterranean CL rhizomes at the base of each plant. Subterranean fruits were not counted due the destructive nature of excavating rhizomes. The goal of this study was to compare the flower phenology as a function of plant age and season in the three floral types. We also evaluate, using limited data, the contributions of CH and aerial CL to reproductive output.
Of the 234 plants followed in this study, 17% flowered. Of these, 90% produced CH flowering stems, 76% produced aerial CL fruits and 24% had CL rhizomes. Plants showed temporal separation in flower type by season with little overlap. CH flowering stems occurred from January to May while aerial CL fruits occurred from June to January followed by CL rhizomes from July to February. As plants matured, they generally produced CH flowers before CL fruits. However, 37% of plants initiated CL fruit production prior to CH flowering; rhizomes were always produced after aerial CL fruiting. Plants initiated CH flowering at a median age of 19 months (7-38 months), aerial CL fruits at 23 months (11-41 months) and rhizomes at 29.5 months (16-44 months). Aboveground reproductive output in P. lewtonii is dominated by chasmogamy. CH fruit production, estimated from prior studies, is a mean of 46 mature fruits per plant (range 12-157 fruits) annually. In our study, plants produced a mean of 12 aerial CL fruits per plant (range 1-79 fruits) annually. Following patterns of CH and CL provides new information on the phenology of the three floral types and aboveground reproductive output of a rare Polygala. This research has added to the limited data on cleistogamy in perennial plants and leads to more questions on the contributions of each type to subsequent recruitment and population growth.


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1 - Archbold Biological Station, Plant Ecology Program, 123 Main Drive, Venus, FL, 33960, USA
2 - Archbold Biological Station, 123 Main Drive, Venus, FL, 33960, USA

Keywords:
cleistogamy
phenology
reproductive biology
rare plant.

Presentation Type: Oral Paper:Papers for Sections
Session: 52
Location: Salon 6/The Shaw Conference Centre
Date: Tuesday, July 28th, 2015
Time: 1:45 PM
Number: 52001
Abstract ID:170
Candidate for Awards:None


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