Abstract Detail

Ecological Section

Smith, Stacy A. [1], Menges, Eric S. [1], Faivre, Amy [2].

Demography and reproductive ecology of Euphorbia rosescens, a threatened perennial herb endemic to Florida scrub.

Euphorbia rosescens, is one of five Euphorbia species endemic to the southeastern coastal plain. Described in 2002, E. rosescens is a threatened perennial herb restricted to a 50 km range on Florida’s Lake Wales Ridge, and found exclusively in Florida scrub on well-drained white sands. Since 2004, we have characterized the habitat and documented life history traits in 13 sub-populations among 48 1-m² quadrats. Monthly, March to July, we have documented survival, reproductive stage, size, gender, and reproductive output of over 1,000 permanently marked individuals. Separately, we conducted an intensive study on flowering phenology and fruit set to address questions on gender expression, critical stages of stigma development, and seed production. Prior to our work, there have been no previous studies on this species’ biology beyond its description.
Individuals are short statured but long-lived and deeply rooted. Populations show dynamic but seasonally consistent fluctuations in stem densities. Inter-annual aboveground dormancy is common, with less than 20% of individuals experiencing dormancy over one year. Annual flowering among study populations ranges from 12% to 23% and fruit set is infrequent and sporadic. Flowers are unisexual and are enclosed within a cyathium. Cyathia develop acropetally, are arranged on compound inflorescences, and may be one of three sex morphs; female, male, or hermaphrodite. Plants either contain entirely female cyathia, entirely male cyathia, or less frequently a combination of male and hermaphrodite cyathia (functionally andromonoecious). Populations are spatially segregated by sex, with groups of individuals bearing female cyathia isolated from mixed patches of both male and functionally andromonoecious individuals. In functionally andromonoecious individuals, hermaphroditic cyathia are produced first and succeeded by male cyathia at higher levels. We have observed fruit maturation only within mixed populations, and have found only one viable seed during the course of our study. No seedlings have been documented in wild populations. While habitat loss and fragmentation remain the major threats to the persistence of rare and endangered plant species, low reproductive success may also contribute to extinction risk.

1 - Archbold Biological Station, 123 Main Drive, Venus, FL, 33960, USA
2 - CEDAR CREST COLLEGE, Department Of Biological Sciences, 100 COLLEGE DR, ALLENTOWN, PA, 18104-6196, USA

Keywords:
Demography
Reproductive ecology
perennial herb
Florida
Euphorbia.

Presentation Type: Oral Paper:Papers for Sections
Session: 1
Location: Firs South/Boise Centre
Date: Monday, July 28th, 2014
Time: 8:00 AM
Number: 1001
Abstract ID:71
Candidate for Awards:None