BEACH, SHANNON E.1*, JANICE M. COONS1, HENRY R. OWEN2, BRENT L. TODD2, and MARY ANN L. SMITH1. 1Department of Natural Resources and Environmental Sciences, University of Illinois, Urbana, IL 61801; 2Department of Biological Sciences, Eastern Illinois University, Charleston, IL 61920. - Comparison of seed production and germination in three distinct colonies of Lesquerella ludoviciana.
Lesquerella ludoviciana (Nutt.) S. Wats. (silvery bladderpod)
is an endangered, sand prairie plant in Illinois, where its only known
habitat is the Henry Allen Gleason Nature Preserve. Three colonies are
found within the preserve: North Bowl upper, North Bowl lower, and
South Bowl. Objectives were to compare seed production and germination
in these colonies. Stages of plant development (seedlings, vegetative,
and reproductive), flower stalks, flowers, and fruits were counted in
each colony on May 4, June 1, June 16, and July 16, 2000. Seed was
collected from each colony on June 1 and 16, 2000. On June 1, seed was
divided into early (lower portion of the flower stalk) and late (upper
portion of the flower stalk) flowering groups. On June 16, only seed
of the late flowering group remained on plants. Thus, three seed lots
of differing maturity were tested. Seeds were germinated in petri
dishes at 25ēC in continuous light, and counted every two to three
days. Seed production was estimated using reproductive plant density,
fruit numbers, and seeds per fruit. The three colonies varied greatly
in seed production. The North Bowl lower produced ten times more
seed than the South Bowl, and sixty times more seed than the North
Bowl upper. Differences in seed production in each colony are due to
many factors including: area (South Bowl 270 m2, North
Bowl, upper 1025 m2, North Bowl, lower 3248
m2), density of reproductive plants (South Bowl 1.4
plants/m2, North Bowl, upper 0.1 plants/m2,
North Bowl, lower 1.1 plants/m2), and presence of other
plant species. Overall, germination percentages ranged from 20% to
66%. No colony differences in germination were observed. For each seed
lot, a different colony exhibited better germination. Thus, no
differences in germination were found due to colony but the seed
production differed greatly between the colonies.
Key words: Brassicaceae, endangered plants, Lesquerella ludoviciana, seed