Small Whorled Pogonia

Isotria medeoloides

Description

Small whorled pogonia, Isotria medeoloides, is an herbaceous perennial with slender, hairy, fibrous roots that radiate from a crown or rootstock. The five or six milky-green or grayish-green, elliptic and somewhat pointed leaves (four leaves in some vegetative plants) are displayed in a whorl at the apex of a smooth, green stem. I. medeoloides flowers from mid-May in the south to mid-June in the northern part of its range. A single yellowish-green flower, or occasionally flower pair, stands in the center of the whorl of leaves. An individual plant is usually single-stemmed, although two or more stems may occur; however, closely grouped double stems may in fact be two single plants. Because of the difficulty in differentiating double stemmed plants from closely neighboring plants, population estimates are often based on the number of stems, as opposed to the number of plants. Scientific research has not completely established the dormancy period of these plants. Some studies have indicated three years, some four years, and others that dormancy may vary by year and by site.

I. medeoloides can be confused with I. verticillata (large whorled pogonia), the only other species in the genus Isotria. Characteristics that distinguish I. medeoloides from I. verticillata include the stem and flower color, the relative lengths of the sepals and petals, and the length of the stem of the fruit capsule in relation to the length of the capsule itself. Colonies of I. verticillata are often found near colonies of I. medeoloides in the extensive region in which they occur together. They have also been reported to grow mixed together.

Habitat

I. medeoloides occurs both in fairly young forests and in maturing stands of mixed-deciduous or mixed-deciduous and coniferous forests. The majority of small whorled pogonia sites share several common characteristics. These may include sparse to moderate ground cover in the microhabitat (except when among ferns), a relatively open under-story canopy, and proximity to old logging roads, streams, or other features that create long-persisting breaks in the forest canopy. The soil in which the shallow-rooted small whorled pogonia grows is usually covered with leaf litter and decaying material. The spectrum of habitats includes dry, rocky, wooded slopes to moist slopes or slope bases crisscrossed by vernal streams.

Distribution

Vermont, New York, Maryland, Missouri, and the District of Columbia only have historic sites for the small whorled pogonia. The habitat of many of this orchid's known historical sites has been destroyed: sites in Vermont, Maryland, New Jersey, and the District of Columbia were lost to habitat destruction through development. Recent intensive efforts to relocate historical sites in eastern Pennsylvania, New York, Vermont, and Missouri have been unsuccessful.

I. medeoloides is widely distributed with a primary range extending from southern Maine and New Hampshire through the Atlantic seaboard States to northern Georgia and southeastern Tennessee. Outlying colonies have been found in the western half of Pennsylvania, Ohio, Michigan, Illinois, and Ontario, Canada.

There are three main population centers of I. medeoloides. The northernmost concentration, comprising 66 sites in 1993, is centered in the foothills of the Appalachian Mountains in New England and northern coastal Massachusetts, with one outlying site in Rhode Island. A second grouping of 18 sites is located at the southern extreme of the Appalachian chain in the Blue Ridge Mountains where North Carolina, South Carolina, Georgia, and Tennessee join. The third center, with 13 sites, is concentrated in the coastal plain and piedmont provinces of Virginia, with outliers in Delaware and New Jersey. Seven sites scattered in the outlying States and Ontario are considered disjunct populations.

I. medeoloides was listed as endangered on September 10, 1982. At that time, records for the species were known from 48 counties in 16 states and Canada, though there were only 17 extant sites, in 10 states and Ontario, Canada. These sites had less than 500 stems. Subsequent searches led to the discovery of many new sites. In 1991, 86 sites in 15 states and Canada were known. By 1993, 17 additional sites in New Hampshire and one site in Maine were discovered, bringing the total to 104 extant sites.

Maine and New Hampshire account for 57% (59 out of 104 sites) of all of the known I. medeoloides sites, and only 15 of these locations are protected.

Threats

I. medeoloides and its habitat continue to be vulnerable to development pressures throughout its range, although recovery activities carried out by Federal and State agencies, private organizations, and the academic community since its original listing as endangered has tripled the number of extant sites, of which 48% are afforded some level of protection. With the exception of a few states, the upland habitat in which it is found receives limited protection through State or Federal regulatory means when occurring on private land.

Residential and commercial development are primarily responsible for the destruction of I. medeoloides habitat. A large New Hampshire population of I. medeoloides has been destroyed since listing by the construction of summer housing, and a second population discovered in 1992 of more than 30 stems faces potential destruction within the next few years as the habitat is developed for a subdivision. One of the larger sites in Virginia will most likely be destroyed within the next few years as its habitat and adjoining suitable habitat is developed for housing. Without voluntary landowner protection, many more I. medeoloides populations could be destroyed as development pressures increase.

Indirect habitat destruction from development can occur as roads, power lines and sewer mains are designed to connect settled areas. Housing developments may also cause the alteration of habitat parameters by creating large, permanent openings in the canopy that in turn encourage denser under-story growth. Disturbance to populations through increased visitation from people and pets might also cause unintentional direct damage to plants, eventually leading to a decline in affected populations.

This plant primarily appears to reproduce sexually, though little is known at this time regarding seed dispersal and seed banking. The formation of barriers to seed dispersal, either through development of adjacent habitat or from logging or land clearing, may prevent the recolonization of suitable habitat by naturally declining populations. Careful and selective logging may not be harmful to a population; however, heavy timbering and clear-cutting may have long-term impacts on I. medeoloides populations and their habitat. The creation of logging roads and use of heavy machinery that severely alters soil composition could significantly modify the habitat and cause the direct loss of plants.

The collecting of this plant by wildflower garden enthusiasts for transplanting is a potential threat of some magnitude, as the rarity of this orchid may inflame their interest. One landowner in North Carolina was literally harassed by orchid and wild-flower enthusiasts when a local garden club publicized the location of his I. medeoloides population. Furthermore, vandalism of populations (either out of capriciousness or for private collections) whose locations were publicized continue to be documented.

Herbivory by white-tailed deer and invertebrates like slugs and camel crickets is a threat of currently unknown extent. Increasing development pressure near I. medeoloides populations results in the concentration of deer onto smaller parcels of woodland and may decrease local hunting pressure on suburban deer populations. As the local deer herd increases and is forced onto less land, there is a greater likelihood of herbivory on I. medeoloides. The magnitude of threat in Virginia from deer browse of I. medeoloides populations may be second only to development of its habitat. The precipitous decline of a large Virginia population located near a housing development appears to be primarily due to grazing. However, symbolic fencing placed around four subpopulations appears to have prevented deer from grazing on the orchids. No plants were observed to have been browsed in 1993; prior to the fencing a majority of the plants were damaged by deer browse. Wild pigs can trample and uproot I. medeoloides plants; rabbits have been known to eat the plants in the southern portion of the small whorled pogonia's range; and moose have occasionally trampled or eaten the plants in the northern portion of its range.

Recent monitoring results indicate a decline in viability of many of the populations that have been followed over a number of years. It appears that no obvious changes have occurred to the habitat of most of these populations and no causes for this decline have been determined. Though life history and demographic studies have provided some clues to the habitat requirements of this species, there is still a large gap in the understanding of what is required to maintain viable populations. Increased research is needed to refine scientific understanding of the dormancy period of these plants, since it can be difficult to determine whether a plant is dead or dormant.

The inadequacy of regulatory mechanisms continues to pose a threat to I. medeoloides, although the protection it has received to date under statute has been of prime importance in bringing the species from endangered to threatened. Some specific examples of how conservation and recovery for this species has been aided by these actions under law will be given in the following section.

Conservation and Recovery

The history of recent steps to protect this species has progressed in several stages, culminating in the decision to change the status from endangered to threatened. The first Small Whorled Pogonia Recovery Plan was completed in 1985. Its objective was to locate and protect 30 population sites of at least 20 individuals each, with at least 15 of the sites to be located in New England. Upon review of newly obtained life-history and site information, this recovery objective was revised. Viability based on the reproductive status and persistence of a population, as opposed to merely a stem count, became a very important factor in determining the recoverability of this species.

A revised recovery plan was approved in 1992 that established new recovery criteria for the reclassification and delisting of I. medeoloides. Reclassification from endangered to threatened would be pursued when a minimum of 25% of the known and viable 1992 sites were permanently protected, and removal from the Federal list would take place when 61 sites (75% of the 1992 sites) were permanently protected. This protection is established in two ways: through the auspices of a governmental agency/private organization committed to maintaining the I. medeoloides population for the site and through a deeded easement/covenant that effectively commits present and future landowners to protecting the population found on their land, even to the point of allowing the implementation of management activities when appropriate. A set of viability characteristics was formally established; since then an alternative viability definition has been developed for sites located in the southern part of the range based upon information provided by botanists familiar with these small, yet persistent populations.

In addition to site viability and protection, reclassification necessitates that the protected, viable sites be distributed proportionally throughout the species' current range. Site protection should also include a sufficient buffer zone around the populations to allow the potential for natural colonization of adjacent, unoccupied habitat. This high level of landowner commitment to site protection may be critical if it is determined that the species needs management to counteract the loss of nearby unoccupied habitat.

Adequate protection for the purposes of reclassification has been achieved for approximately 50% of the viable New England center populations; 57% of viable populations in the Virginia center; and 100% of the viable populations in the Blue Ridge center. No populations in the outlying states are considered to be viable, though four of the six extant populations are protected.

The recovery program approved in 1992 prescribes continued efforts to protect known I. medeoloides populations and essential habitat, develop habitat management strategies, manage protected sites, monitor sites and determine viability, survey for new sites, investigate population dynamics and species biology, and provide public information and education.

Federal, state, and local agencies are continuing efforts to improve the status of the species. The National Park Service in Virginia has provided funding for research and monitoring, while seeking ways to prevent disturbance to sites under its jurisdiction. The Department of Defense has also facilitated searches and monitoring of populations at two bases in Virginia. In Georgia, the U.S. Forest Service conducts plant surveys in areas potentially affected by management activities, regularly monitors known sites, and has been particularly successful in finding new sites. In 1993, two sites were located on the White Mountain National Forest in New Hampshire. Base maps for potential I. medeoloides habitat were developed for the White Mountain National Forest; the Forest Service now consults the Service on all activities proposed for those area. Consultations under section 7 of the Endangered Species Act can provide protection for this species; a road and sewer main near an I. medeoloides population in Virginia were re-routed to avoid direct destruction of the plants and their habitat. Coordination with state and local agencies, as well as private developers, has resulted in the avoidance of adverse impacts to I. medeoloides and its habitat. In Connecticut, a trail was re-routed to avoid a population in a state forest.

For those populations on private lands, conservation easements or agreements with the landowners have been actively pursued. Eight sites are on lands owned by private conservation organizations, while two other sites have deeded conservation easements ensuring the protection of the plants and their habitat. Some state agencies pursue voluntary registration of I. medeoloides sites. While such registration does not guarantee habitat protection, it does seek to recognize the importance of the site in the hopes of voluntary protection on the part of the landowners. Recovery efforts have been directed toward research and environmental education. A predictive habitat model was developed using Geographical Information System (GIS); 10 additional sites were discovered in 1993 using maps delineating potential habitat. Educational materials in the form of posters, brochures and fact sheets were designed and made available to the general public.

Ongoing research includes the investigation of mycorrhizal relationships, and habitat manipulation to encourage or stabilize I. medeoloides populations. Mycorrhizal associations are important factors in the germination and seedling establishment of most orchids. Though a mycorrhizal fungus was isolated from the closely related I. verticillata, host-specific mycorrhizae have not been identified for I. medeoloides. Alterations to I. medeoloides habitat that adversely affect the mycorrhizae would also result in adverse impacts to the orchid. However, until the specific mycorrhizal associate is determined, it will be difficult to understand the effects of subtle habitat alteration on the orchid or the fungal community.

As adjacent, suitable habitat is developed, precluding the natural colonization of suitable habitat, management may be the only alternative for maintaining viable populations. It may be vital to develop habitat management strategies for existing sites in order to maintain self-sustaining populations. Without the knowledge of key habitat characteristics, management and the precise identification of potential habitat will be impossible. Soil type (including texture and moisture), nutrient availability, overstory cover, understory density, slope position and aspect are some of the habitat characteristics that might be important factors in population viability. Other unknown parameters include the variation of climatological factors and relative humidity throughout the species' range, and how these differences impact population stability, plant reproduction, recolonization and viability.

The dearth in knowledge of habitat characteristics and life history information may result in the further decline of many populations through benign neglect.

Contacts

U.S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
1 Federal Drive
BHW Federal Building
Fort Snelling, Minnesota 55111
Telephone: (612) 713-5360
http://midwest.fws.gov/

U.S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
300 Westgate Center Dr.
Hadley, Massachusetts 01035-9589
Telephone: (413) 253-8200
Fax: (413) 253-8308
http://northeast.fws.gov/

U.S. Fish and Wildlife Service
New England Field Office
22 Bridge Street—Unit 1
Concord, New Hampshire 03301-4986
Telephone: (603) 225-1411
Fax: (603) 225-1467

Reference

Brumback, W.E., and C.W. Fyler. 1988. "Monitoring of Isotria medeoloides in New Hampshire—1988." Wildflower Notes 3 (1): 32-40. New England Wild Flower Society. Framingham, Massachusetts.

Dixon P., and R. Cook. 1988. "Attempts to RelocateIsotria medeoloides in New York State." Unpublished report. Cornell Plantations, Ithaca, New York. 3 pp.

Mehrhoff, L.A. 1980. "The Reproductive Biology of the Genus Isotria (Orchidaceae) and the Ecology of Isotria medeoloides." M.S. Thesis, University of North Carolina, Chapel Hill, North Carolina. pp. 17-23.

Mehrhoff, L.A. 1989a. "Reproductive Vigor and Environmental Factors in Populations of an Endangered North American Orchid, Isotria medeoloides (Pursh) Rafinesque." Biological Conservation 47: 281-296.

Mehrhoff, L.A. 1989b. "The Dynamics of Declining Populations of an Endangered Orchid, Isotria medeoloides." Ecology 70 (3): 783-786.

Rawinski, T. 1986a. "Element Stewardship Abstract for Isotria medeoloides (Pursh) Raf." Unpublished report. Eastern Heritage Task Force, The Nature Conservancy, Boston, Massachusetts. 16 pp.

Rawinski, T. 1986b. "Vandalism of the Small Whorled Pogonia." Endangered Species Technical Bulletin. 11 (12): 6.

Sperduto, M. 1993. "Use of a Geographic Information System (GIS) to Predict Potential Habitat for Isotria medeoloides (Pursh) Raf. in New Hampshire and Maine." M.S. Thesis, University of New Hampshire, Durham, New Hampshire. 106 pp.

U.S. Fish and Wildlife Service. 1982. "Endangered and Threatened Wildlife and Plants; Determination of Isotria medeoloides (Small Whorled Pogo-nia) to be an Endangered Species." Federal Register 47 (176): 39827-39831.

U.S. Fish and Wildlife Service. 1985. "Small Whorled Pogonia Recovery Plan." Newton Corner, Massachusetts. 38 pp.

U.S. Fish and Wildlife Service. 1992. "Small Whorled Pogonia (Isotria medeoloides ) Recovery Plan, First Revision." Newton Corner, Massachusetts. 75 pp.

U.S. Fish and Wildlife Service. 1993. "Endangered and Threatened Wildlife and Plants; Proposed Rule to Reclassify the Plant Isotria medeoloides (Small Whorled Pogonia) from Endangered to Threatened." Federal Register 58 (200): 53904-53909.

Vitt, P. 1991. "Conservation of Isotria medeoloides : AFederally Endangered Terrestrial Orchid." M.S. Thesis, University of Maine, Orono, Maine. 40 pp.

Ware, D.M.E. 1991. "Small Whorled Pogonia" (pp.95-97). In: Karen Terwilliger, coord. Virginia's Endangered Species. Nongame and Endangered Species Program, Virginia Department of Game and Inland Fisheries. The McDonald and Woodward Publishing Company, Blacksburg, Virginia. 672 pp.