Plant Species Biology Summary for Umbrella Sedge
Illinois Department of Natural Resources
Division of Natural Heritage

The following information is derived largely from monitoring records of the Illinois Department of Natural Resources but some may come from the literature and other sources. It relates to the biology of the species in Illinois.

Species: Cyperus grayioides, Umbrella Sedge

Compiler: John E. Schwegman, Illinois Department of Natural Resources

Date of Most Recent Update: May 8, 1992

Location of Monitored Populations: H. A. Gleason Nature Preserve, Mason County, IL

Plot Type and Size, Population Size: Partial circular demographic plot with 3 meter radius for 180 degrees (14.13 meters square). Initial population was 35 fertile and 2 juvenile plants increasing to estimated 155 flowering and 10 sterile after recovery from drought.

Monitoring Dates that are Basis for this Analysis: July 1987 through July 1991.

Variations from Normal Conditions while Monitoring: A severe drought occurred in 1988 and continued through 1989. An exceptionally early severe cold temperature occurred in early December of 1989 (-20 F). The spring and summer of 1990 were much wetter than normal.

Range of Natural Communities: Open dune sand to open sandy spaces in early successional sand prairie.

Range of Plant Communities: Aristida tuberculosa-Panicum villosissimum-Cyperus grayioides to Schizachyrium scoparium-Opuntia humifusa.

Range of Soil and Substrate: Sand.

Range of Slope and Aspect: Mostly level to gentle slopes, any aspect.

Range of Shading or Crown Cover: Mostly full sun, but some stands have slight shading for part of the day.

Flowering Dates in Illinois: Late June through mid August. Flowering can be delayed by dry conditions and start soon after rains as late as mid August.

Fruiting Dates in Illinois: Mid July to mid August.

Known Phenotypic Variation: None observed.

Known Pollinators in Illinois: Wind pollinated.

Reproductive Mode: This bulbous perennial herb reproduces by seed and offset bulbs from existing bulbs.

Conditions for Sexual and Asexual Reproduction: Seeds germinate in spring on open sand under high moisture, high light and low competition conditions. Seed stratification needs are unknown, but abundant germination in 1990 followed two years of virtually no seed production indicating that most of the germinating seed had been in the soil nearly 3 years and some of it potentially longer. Observations of the appearance of this species from a seed bank where dozer work created open bare sand indicates it is a long term seed banker. At this site no plants had been seen at this well known area for 15 years prior to its appearance after disturbance. New bulb growth begins in June as a white radical from the base of an existing bulb and presumably matures by fall. Older plants develop strings of bulbs that tend to form rings, giving them a broad circular pattern of leaves. Such strings of bulbs might be mistaken for rhizomes upon casual observation.

Known Diseases: Some have an unknown leaf blight that spots leaves with red then turns brown. Others exhibit chlorosis or paleness at monitoring time. A blighted plant in a successional site near oak seedlings seemed to be dying of the disease. In the open high quality demographic site, the blight was present but caused no problem. The chlorosis seemed to cause no problem.

Known Grazers and Parasites: No evidence was ever seen of anything eating this species, vertebrate or invertebrate. No parasites were noted.

Known Problems with Exotic Species: None noted.

Known Response to Fire: No opportunity to observe response to fire in this study. Where it grows, fuel is so low that fire would not reach it in good dune habitats. In early succession prairie, fire may impact it. To the extent that fire prohibits succession and helps retain blowouts and open sand, it should benefit this species.

Known Mortality Factors: Of 35 sexually mature plants marked in 1987, 31 were dead and gone in 1990 after two consecutive years of severe drought in 1988 and 1989. Drought was observed to be the cause of mortality of most of these plants and was probably the cause of all deaths. At an early successional prairie plot, some mortality was attributed to burial by oak leaves, competition with grasses and sedges and possibly leaf blight.

Known or Suspected Responses to Environmental Stress: In response to the stress of low moisture, some plants died, some delayed flowering until rains came, and some survived but did not flower.

Known Shifts in Plant Vigor: Plants reduced the number of flowering stalks or did not flower atall in response to drought. Those that survived drought were able to greatly increase flowering stems the first year after a wet growing season. An example of this is plant #16 which had 9 flowering stems in 1987 then none in drought years 1988 and '89 and even none in the wet year of 1990. It returned in 1991 with 15 flowering stems.

Known "Resting" (of Perennial Herbs): No plants were observed to disappear and then return.

Summary of Apparent Factors Regulating Size and Health of Populations:

The species is vulnerable to moisture stress mortality, even in ideal habitat if drought is severe. Populations also decline and disappear as its habitat succeeds to perennial herbs and young trees. This mortality seems related to increased competition for moisture with other plants, burial with tree leaves, possibly reduction in light levels and increased vulnerability to blight. It is a seed banking species that can survive at least 15 years and possibly much more in the seed stage. It germinates readily from its seed bank if abundant moisture, high sunlight and bare sand conditions prevail. Fire suppression and the reduction of grazing ungulates that followed the settlement of Illinois have fostered the succession of barren sand vegetation required by this species to unsuitable perennial herb and forest habitats.