Foliar Indicators of Age in Louisiana Native Dwarf Palmetto Plants Jim Wandersee, Ph.D. William LeBlanc Alumni Association Professor of Biology Education LSU Department of Curriculum & Instruction & LSU AgCtr Burden Research Center

Introduction Dwarf Palmetto (Sabal minor) is a native Louisiana plant Understory palm found in the Southeast in swamp forests and on floodplains Slow growing to hundreds of years of age First described in 1691 by Le Clercq in an account of La Salle’s explorations of the Mississippi River

Dwarf Palmetto Botanical Classification Family: Palmae Genus: Sabal Specific epithet: minor

The Palm Family (Palmae) Found in sub-tropics and tropics Third-largest monocot family Contains >2,700 species in >200 genera Greatest diversity in SE Asia & Malaysia, Central America, African Congo region, and N. Madagascar (Uhl & Dransfield, 1987)

Range: Distribution of Sabal minor Coastal plains of the South Atlantic Seaboard and the states bordering the Gulf of Mexico Louisiana is the ONLY state to be completely included in its range States partially within its range are NC, SC, GA, FL, AL, MS, & TX

S. Minor Inflorescence Structure & Fruit Flowering season: mid-June to July

Variablity in Stature Sabal minor data recorded in the botanical literature suggest: Height MINIMA: ~40 centimeters (mature) Height MAXIMA: ~5.8 meters (mature) As a rule of thumb, height increases from east to west (e.g., Panhandle of Florida to West Texas). Caulescent populations have not been observed in the eastern half of its range (Ramp, 1989).

Research Program Goals To improve both scientific understanding and public understanding of one of Louisiana’s most widespread and “signature” native plant species, Sabal minor.

Research Target: Phase I To find the simplest way of estimating the age of individual Sabal minor plants—by investigating the predictive value of selected foliar variables that are supported by a review of relevant research literature in plant ecology and in horticulture.

Research Plots Phase I: Full Sun Specimens Will yield a conservative age estimate Plot #1: 3-acre Barton arboretum area of BRC ~40 individuals of varying pre-reproductive age Phase II: Forest Understory Specimens In full range of stages [#1-#12] of development 3 native population plots within BRC’s 100-acre forest

Methods Foliar Variables under study: Leaf surface area for largest leaf Maximum leaf thickness for largest leaf Leaf oven dry mass (estimated by regression equation via petiole blade-basal width for largest leaf) Total number of leaves per plant Total number of leaf scars per plant, plus (see next slide)

Methods continued Foliar Variables under study: Munsell Plant Tissue Color Chart ratings for the largest and smallest leaves Leaf nutrient analysis of 21 elements via ICP spectroscopy for largest and smallest leaves These variables will be correlated to historically established, age-benchmark specimens, and to pre- and post-reproductive features described by Ramp (1989).

Researcher Memberships American Association for the Advancement of Science Botanical Society of America Crosby Arboretum LSU 15º Laboratory National Association of Biology Teachers National Tropical Botanic Garden International Palm Society Royal Horticultural Society