Status of the known populations of the Virginia bunchflower (Melanthium virginicum) in Illinois

Castanea, Jun 2002 by Moorehouse, Angella, Mankowski, Anne, McClain, William E, Ebinger, John E

ABSTRACT

Virginia bunchflower (Melanthium virginicum L.) is known historically from wet-mesic prairie in 17 counties located primarily in west-central Illinois. Due to the loss of wet-mesic prairie, plants within six counties were extirpated during the 1800s, and populations within an additional six counties were extirpated within the last 15 years. This taxon is currently known from thirteen populations in three counties. These populations were studied over a three year period, beginning in 1998 and ending in 2000. Flowering varied considerably from year to year. Although large bunchflower colonies remain that contain over 800 plants, only two populations are currently protected. Population loss is expected to continue, documenting the need for greater protection and the introduction of this plant into suitable wet-mesic prairie restorations within its historic range.

INTRODUCTION

Virginia bunchflower (Melanthium virginicum L.) has a sporadic distribution throughout much of the eastern United States where it occurs in wet meadows, bogs, swales, low thickets, savannas, and moist woodland edges from New York west to Iowa and Minnesota, and south to Texas and Florida (Fernald 1950, Gleason and Cronquist 1991). A member of the Liliaceae (sensu Gleason and Cronquist 1991), this perennial herb is characterized by a thick rhizome, an erect, stout stem up to 1.7 m in height, and numerous basal and a few cauline, linear, acuminate leaves. Blooming occurs in late June and July in Illinois, and the terminal panicle consists of 3-10 spreading branches supporting short-stalked, perfect and staminate, creamy-- white, turning pale green, 3-merous flowers to 25 mm in diameter. Mature plants are characterized by multiple shoots, each of which may produce an inflorescence (Fernald 1950, Gleason 1952, Correll and Johnson 1970, Gleason and Cronquist 1991).

In Illinois, Melanthium is largely restricted to the west-central counties where it was first reported by S. B. Mead (1846) from Hancock County (Kibbe 1952). Jones and Fuller (1955) reported this plant from 14 counties, and subsequent updates of the distribution of the vascular flora added one county, bringing the total to 15 (Winterringer and Evers 1960). Mohlenbrock and Ladd (1978) listed these same 15 counties for this taxon.

The habitat for Melanthium is wet-mesic prairie located in swales or along streams. Due to the loss of populations of this plant, the Illinois Endangered Species Board listed it as threatened in 1999 (Illinois Endangered Species Board 1999). Concern increased for this taxon when the authors could not relocate several populations known to exist within the last 15 years. The purpose of this study was to determine the current status of Melanthium populations in Illinois, and to recommend protection and recovery measures.

DESCRIPTION OF THE STUDY AREA

Populations of Melanthium are known from the Springfield Section of the Grand Prairie Division, the Galesburg and Carlinville Sections of the Western Forest-Prairie Division, and the Effingham Plain Section of the Southern Till Plain Division (Schwegman 1973).The original vegetation was a mixture of forest and prairie. Forest predominated on slopes and lowland areas whereas sizeable areas of prairie were present on the uplands. The largest of these were Allen's, Apple Creek, Buckhorn, Carthage, Canton, Diamond Grove, Edmonson's, Froggy, Granger's, Hancock, and String Prairies (McClain 1997). No remnants of these prairies survive, except for linear strips along railways.

The climate of west-central Illinois is a continental type, characterized by hot summers and cold winters. The average annual precipitation is 95 cm, which falls mostly as rain during the period May through September. Approximately 40 days will have a maximum temperature of 32 deg C or greater. Approximately 15 days during December through February can be expected to have subzero temperatures. The length of the growing season ranges from 180 to 195 days (Bushue 1979).

METHODS

The distribution of Melanthium in Illinois was determined by examining specimens from herbaria (DEK, EIU, F, KNOX, ILL, ILLS, ISM, MO, MOR, MWI, SIU), consulting literature, and contacting the state's field botanists. Known locations for Melanthium, as recorded on herbarium specimens, were visited during the field surveys, and searches were made for plants. However, no field surveys were conducted in Peoria and McLean Counties due to the lack of specific location data. At sites where Melanthium was present, the predominant vegetation was noted, and the number of inflorescences was recorded at each site during July in the summers of 1998, 1999, 2000, up to a maximum of 800. Due to the dense vegetation at the time of flowering in July, it was impossible to obtain an accurate count of all individuals of Melanthium. Consequently, a count of vegetative plants was made early in the spring of 2000 to determine population densities. The nomenclature follows Mohlenbrock (1986).