Development of the Endangered Kankakee Mallow (Iliamna remota, Greene) When Affected By Light Intensity

M.C. Jernegan, A.L. McDonnell, S.M. Haley, B.W. Craven, J.A. Cummings, and J.M. Coons
Eastern Illinois University, Department of Biological Sciences.
 

Abstract

Iliamna remota Greene (Malvaceae), Kankakee mallow, is an endangered species in Illinois. In 1984, it was on the verge of extinction when a recovery plan began to eradicate invasive woody shrubs, mainly Lonicera maackii (Amur honeysuckle). These shrubs compete with native species partly by shading. Recent lack of management is threatening the I. remota population. Our objective was to simulate shade from in situ canopy on development of I. remota. Seeds were germinated in vermiculite, and seedlings were transplanted into a hydroponic system in two growth chambers with a 16h/8h (light/dark) photoperiod at 25ºC. Light intensity was either 248 ± 13 µmol/m2/sec (high light) or 63 ± 6 µmol/m2/sec (low light). Development was quantified by measuring number of leaves, fresh and dry weight, shoot height, leaf area, root length, and root volume. After 3 weeks, plants grown with high light were more developed with more leaves on both main stems and side branches, taller shoots, greater leaf area, greater root volume, longer roots, and greater fresh and dry weights of shoots and roots, than those with low light. Thus, light intensity greatly affected the development of I. remota, stressing the importance for management to control shrubs to preserve I. remota.

Introduction
 

Iliamna remota Greene (Malvaceae), Kankakee mallow, is a state endangered plant that is endemic to Langham Island in the Kankakee River in Kankakee County, Illinois (Herkert and Ebinger, 2002). In 1983, L. maackii (Rupr.) Maxim and Rosa multiflora Thunb, both woody, invasive shrubs, were out competing I. remota, resulting in declines in the population size (Schwegman, 1984). Under a canopy of these woody plants light availability is limited for lower growing plants. In most plant species, variations in light intensity have morphological and physiological effects (Rice and Bazzaz, 1989). For many native species, limited light availability decreased population sizes even to extinction. In previous studies, removal of dense thickets of Lonicera maackii increased diversity and the numbers for individuals of each native species (McDonnell et al. 2005). I. remota grows mostly in “full sun” or “open areas” and typically is intolerant of dense shade and shrub competition (Glass et al., 2003; Schwegman, 1984). Information regarding growth of I. remota with low light would be useful for management plans with the goal of preserving the I. remota population on Langham Island.

Methods

• Kankakee mallow (Iliamna remota Greene) seeds were purchased from Prairie Moon Nursery.

• Seeds were dipped in 80°C water for 20 seconds to break dormancy.

• Seeds were grown in vermiculite until 2-4 true leaves developed.

• Seedlings were transplanted into a hydroponic system.

• Hydroponic system consisted of aeration tubing hooked to an Aquarium pump inserted into plastic containers (2.2 liters) with a nutrient solution.

• Nine seedlings were placed in each of two Conviron® growth chambers at 25°C with 16h light/8h dark, and a light intensity of 248 ± 13 µmol/m2/sec (high light) or of 63 ± 6 µmol/m2/sec (low light).

• Development was quantified by measuring number of leaves, fresh and dry weights, shoot height, leaf area, root length, and root volume.

• Data were analyzed using one-way analysis of variance.

• The objective of this study was to quantify effects of light intensity on growth of I. remota seedlings to simulate canopy shade.

Results

Significance

• Plants in high light developed larger shoots and roots than those in low light demonstrating adverse effects of low light intensity on development of I. remota.

• High light plants had lower or equal shoot:root ratios than low light plants suggesting more photosynthates into roots than shoots.

• Shade from invasive woody shrubs such as L. maackii and Rosa multiflora will have a detrimental effect on growth of I. remota by reducing light.

• Restoration efforts should reduce competition around I. remota. New populations should be planted in open areas.

• Significant differences between the two light intensities for number of leaves developed at week two.

References

1.Glass, W., J.E. Schwegman, R.R. Heidorn, and W.E. McClain. 2003. Twenty years of management of the endangered Kankakee mallow (Iliamna remota Greene, Malvaceae) on Langham Island, Kankakee County, Illinois. Illinois Department of Natural Resources Report, Springfield IL. p.1-20.
2.Herkert, J.R. and J.E. Ebinger. 2002. Endangered and Threatened Species of Illinois: Status and Distribution, Volume 1-Plants. Illinois Endangered Species Protection Board. Springfield, IL 47pp.
3.McDonnell, A.L., A.M. Mounteer, H.R. Owen, and B.L. Todd. 2005. Influence of stem cutting and glyphosate treatment of Lonicera maackii, an exotic and invasive species, on stem regrowth and native species richness. Transactions of the Illinois State Academy of Science 98:1-17.
4.Rice, S.A. and F.A. Bazzaz. 1989. Quantification of plasticity of plant traits in response to light intensity: comparing phenotypes at a common weight. Oecologia 78: 502-507.
5.Schwegman, J.E. 1984. State of Illinois Recovery Plan for Iliamna remota Greene. Division of Forest Resources and Natural Heritage, Illinois Department of Conservation. Springfield IL p.1-3 and 9-13.