ELEMENT STEWARDSHIP ABSTRACT FOR PYCNANTHEMUM CLINOPODIOIDES July 1, 1994 Stewardship Abstract No.: 016 By: Elizabeth M. Obee State of New Jersey Department of Environmental Protection Division of Parks and Forestry Office of Natural Lands Management CN 404 Trenton, New Jersey 08625 Element Stewardship Abstract Element Stewardship Abstracts (ESA's) are prepared to provide land managers and other conservation workers with current biological and management related information on those species and natural ecosystems that are most important to protect or for which control is most needed. The abstracts organize and summarize data from numerous sources, including the literature and from researchers and managers actively working with the species or ecosystem. The ESA format was originally developed by The Nature Conservancy as a starting point for the stewardship of the many species and ecosystems, or elements, protected by the Conservancy. The New Jersey Office of Natural Lands Management is developing ESA's for those elements that are of particular importance as components of the biota of the state. This includes globally rare plant species that are also listed on New Jersey's official Endangered Plant Species List. The ESA serves several important functions. It helps to identify information gaps and target future research efforts. It provides a standard format for highlighting specific information about a species or community including its management needs. It also allows information to be readily communicated among various preserves, state offices, regional centers, natural heritage programs and private organizations. The ESA is a dynamic document that is continuously updated as new information becomes available. Users are encouraged to contribute their information to the abstract. This sharing of information will benefit all land managers by ensuring the availability of up-to-date information on management techniques and knowledgeable contacts. Please contact the Office of Natural Lands Management for an ESA publication list. It will contain the date of the latest revision to each ESA. Please refer to the abstract number when ordering ESA's. The abstract is a compilation of available information and is not an endorsement of particular practices or products. Element Name: PYCNANTHEMUM CLINOPODIOIDES Torr. and Gray (Lamiaceae) Element Code: PDLAM1N030 Preparer: Elizabeth M. Obee Common Name: Basil mountain mint Description: Habit: Perennial herb up to a meter tall, commonly to 80 cm. For complete description see Grant and Epling (1943). Stem: Slender, 3-7.5 dm, to 1 m with short, axillary branches. Pubescent with short, downcurved hairs or longer spreading hairs or both. Leaves: Short leafy branches originate in the axils of the leaves. Leaf blades are narrowly lanceolate, shallowly serrate or entire, 4-8 cm long and not canescent. The largest leaves average 4.5 to 9.5 cm long by 1 to 2.5 cm wide, on petioles 3 to 6 mm long. The upper leaf surface has scattered hairs and the lower surface has longer spreading hairs especially on the main veins. Inflorescence: Open and distinctly branching as a loose corymb. Leaf-like bracts subtending the inflorescence are either green or canescent on the upper surface. Flowers: Calyces pubescent with short hairs 4-6 mm long. Calyx- teeth sparingly bristle-tipped and ciliate, and the corolla tube 4-5.5 mm long and abruptly narrowed above the middle. Fruits: Nutlets glabrous or sometimes hairy at the tip. Distinctions from Related Species: The identification of members of Pycnanthemum is complicated by hybridization, polyploidy, and intraspecific polymorphism (Carr and Hunter, 1973). P. clinopodioides is similar in appearance to Pycnanthemum incanum (Snyder, in press). P. incanum has slightly wider leaves, up to 5.5 cm wide, with many strongly canescent above. P. clinopodioides has green leaves narrowly lanceolate and rarely as wide as 2.7 cm. P. clinopodioides can be distinguished from narrower leaved species by its more open, distinctly branched inflorescence, bilabiate calyces, which are typically margined with few to several long, multicellular trichomes (Snyder, in press). Also the stems of P. clinopodioides have both long, spreading hairs and also minute curved hairs with tips pointing towards the stem to form a tiny inverted J or U (Snyder, in press). Habitat: P. clinopodioides prefers dry or moist rocky ground of wooded slopes and watersides, as well as dry open ledges, bluffs, and open thickets, frequently over limestone or mafic substrates. Current occurrences include 6-20 locations in Maryland, two in Connecticut, one in Massachusetts, and five in New Jersey. In New Jersey several of these populations were identified in recent years during searches of appropriate habitat (Snyder, in press). Historical populations have been reported from Massachusetts, Connecticut, New York, New Jersey, Pennsylvania, Delaware, District of Columbia, West Virginia, North Carolina, and Indiana. The historical Indiana population may represent a disjunct from the rest of the species' range. The species was once reported from Texas, but may have been misidentified. The Delaware collection has been determined to be a misidentification of P. torrei. A potential specimen from Kentucky is currently awaiting determination (White, pers. comm.). Fifteen to twenty historical records are recorded for the state of Pennsylvania (Kunsman, pers. comm.). Biology/Ecology: The genus Pycnanthemum consists of approx. 20 species located mostly in the eastern U.S., with the center of diversity for the genus located in the mountains of North Carolina (Chambers, 1961, Boomhour, 1941). P. clinopodioides has the most restricted distribution of any Northeastern U.S. Pycnanthemum species (Snyder, in press). This species flowers in July to September, and is considered local or rare throughout its range (Snyder, in press). It was first described by Torrey and Gray in 1842 based on NJ and NY specimens, but questions arose about a possible hybrid status of P. clinopodioides. Gray (1848) considered it a hybrid between P. incanum and P. torrei. P. torrei has a range and habit similar to P. clinopodioides and is also rare (Chambers and Chambers, 1971). Chambers (1962) believed P. clinopodioides to be a hybrid between tetraploid species of the virginianum and incanum species complexes. Grant and Epling (1943) considered P. clinopodioides a valid species but suggested that the species was very variable and may be of hybrid origin between a species of the incanum group and a narrow leaved species such as P. verticillatum (Grant and Epling, 1943). Current authors consider it a valid species not necessarily of hybrid origin (Gleason, 1991; Gleason and Cronquist 1963). A study of chromosome number of Pycnanthemum revealed uncertainty about the taxonomic affinities of P. clinopodioides (Chambers, 1961). Two plants of P. clinopodioides were studied, one tetraploid and one triploid. The triploid was morphologically similar to the tetraploid but sterile, with a high percent of pollen abortion. Meiotic irregularities in the tetraploid indicate the production of chromosomally unbalanced gametes (Chambers, 1961). The chemistry of P. clinopodioides has not been investigated, but it is likely to be similar to that of other mint species for which there have been some preliminary investigations. P. incanum has been identified as a species with a high natural rubber content; more than 1% natural rubber on the whole dry plant basis (Buchanan et al. 1978). This species is widespread over most of its range, but is endangered in Canada (Crins, 1989). P. pilosum, mountain mint, was stated by Pellett (1947) to be "A promising plant which may provide a new crop for essential oil as well as bee pasture." Peppermint and spearmint are the plants most commonly grown within the U.S. for essential oils. Essential oils are used to make a variety of products from chewing gum to soap (Pellett, 1947). The oils from this plant are produced from trichomes on the stem and leaves (Pellett, 1950). The major constituents of the oil from P. pilosum were found to be 80% pulegone, 10% menthone, 3-5% limonene, and 2% menthol (Pellett, 1950). The oil from another species, P. albescens, is known to have odor-blocking and antifungal properties (Eickholt and Box, 1965). P. albescens is a volatile oil similar to peppermint oil, composed primarily of terpenes, with no menthol component. Toxicity tests were investigated with this oil and it was found to be even less toxic to mice than peppermint oil, and thus possibly suitable for human consumption. The lower toxicity is thought to be due to the lack of menthol in this oil (Eickholt and Box, 1965). In Illinois a population of P. virginianum was reported to have a lemony odor instead of the customary minty odor (Sorensen and Matekaitis, 1981). The distribution of P. virginianum within the prairies of Ontario has been studied in relation to soil factors (Faber-Langendoen and Maycock, 1987). It was found to be less common on wet loam soils than on dry-mesic sandy, mesic sandy loam, and wet-mesic sandy loam soils (Faber-Langendoen and Maycock, 1987). This species was also studied within the tallgrass prairies of Wisconsin (Parker et al., 1993). This and other native species were found to be more prevalent on undisturbed sites than disturbed sites near roads were the abundance of exotics increased. The examination of other closely related species of Pycnanthemum may provide some insight into the biological characteristics of P. clinopodioides. However, until studies have been completed which specifically address this species, it will be difficult to make generalizations about the biology and ecology of the species. Determination of Element Occurrence (EO) Quality: An exemplary population is considered 200 or more plants in contiguous habitat (New Jersey Natural Heritage Program, 1993). The number of stems per plant is also an important parameter, as this is a good indication of age and vigor. The species is perennial, rhizomatous, and occurs as scattered patches of individual plants with one or more stems. Any viable population is an occurrence (New Jersey Natural Heritage Program, 1993). Ideal habitat conditions include areas where natural disturbance has not been disrupted, and succession of open habitat by woody vegetation is minimal. Suitable uncolonized habitat should be present. Threats: Loss of habitat due to development and quarrying or by natural succession of woody vegetation is the primary threat to P. clinopodioides. However, hybridization with other Pycnanthemum species may potentially be an additional threat to P. clinopodioides. There appear to be few barriers to interspecific hybridization within Pycnanthemum, and vigorous vegetative reproduction might permit the survival of hybrids with low fertility (Chambers, 1962). Chambers and Chambers (1971) reported that P. clinopodioides is capable of forming both natural hybrids with P. incanum and artificial hybrids when brought into contact with P. pilosum or P. tenuifolium, although the artificial hybrids were slow growing with weak stems. More recent work on hybridization within Pycnanthemum did not include P. clinopodioides (Chambers, 1993). Land Protection Specifications: Protection of populations from development and from elimination by succession both need to be implemented to ensure the survival of this species. This may require active management of disturbance at site locations. The most protected occurrences may be those where the entire watershed in which they occur is protected from development and human disturbance. Recovery Potential: Herbaceous species found in relatively open areas within wooded lands such as P. clinopodioides are often gap-colonizers which benefit from natural disturbances such as windthrows within a mosaic of successional stages. The alteration of this natural process may result in a successional stage dominated by mature woody vegetation of uniform age and the elimination of P. clinopodioides. However, recovery potential of populations should be good as long as a seed source of P. clinopodioides is present near newly available habitat. It is not known whether this species maintains a viable seed bank. Biological Monitoring Needs: Repeated yearly monitoring of the demography of large populations is needed in order to better understand the life history of the species. This would allow for the determination of the life span of individual plants and the amount of seedling establishment and mortality. Threats to the populations could then be assessed on an individualized basis. Searches of potentially appropriate habitat and historical locations for populations is also recommended. Biological Monitoring Procedures: Monitoring should record population size, area, and an estimation of seed set in a given year. Any advances in the successional stage of the surrounding community should be tracked. If any intentional or unintentional manipulation of a population area occurs, the effects of the manipulation should be monitored and recorded. Biological Monitoring Programs: No formal monitoring programs are in place for this species, except for tracking by Heritage Programs in some states. Research Needs: Taxonomic research is needed to verify the identifications of herbarium specimens of P. clinopodioides. Although present taxonomic authors have considered P. clinopodioides to be a valid species, more research on hybridization within the genus is recommended to verify the species status of P. clinopodioides and further investigate a possible hybrid origin of this species. Dr. Kesseli at the University of Massachusetts is currently investigating the potential for hybrid origin of the Massachusetts population (Somers, pers. comm.). Management Needs: The dependency of this species upon partially open areas may require special management. Human disturbance may reduce or increase the amount of habitat suitable for perisitence or recolonization of this species. Periodic disturbance of woody vegetation may be necessary in order to maintain habitat in a suitably open condition. Management at the ecosystem level of watersheds associated with locations of this species may be necessary in order to preserve the overall environmental quality of the habitat. While the species is dependent on some form of disturbance for survival, not all disturbance may be beneficial. One location of P. clinopodioides in Massachusetts occurs within a protected area, but along a roadside. Roadside maintenance for this and any other roadside populations may be detrimental if mowing occurs before seed set for the species. Special accommodations may need to be made to delay mowing until after seed dispersal, in order to encourage the expansion of roadside populations. Summary of Stewardship Needs: P. clinopodioides is a very rare species which may require special management of natural areas in order to ensure survival. Controlling the process of natural succession and/or roadside maintenance may be necessary in order to prevent elimination of the species from habitat it presently occupies. This active management is suggested for appropriate locations in addition to the overall need for protection of land from development. Bibliography for Pycnanthemum clinopodioides Torr. and Gray: Boomhour, G.E. 1941. A taxonomical study of the genus Pycnanthemum (Labiatae). Ph.D. Thesis, Duke University. Buchanan, R.A., I.M. Cull, F.H. Otey, and C.R. Russell. 1978. Hydrocarbon- and rubber-producing crops: Evaluation of 100 U.S. plant species. Economic Botany 32: 146-153. Carr, R.K., and G.E. Hunter. 1973. Flavonoid studies of Pycnanthemum: Labiatae. J. Tenn. Acad. Sci. 48: 2-5. Chambers, H.L. 1961. Chromosome numbers and breeding systems in Pycnanthemum (Labiatae). Brittonia 13: 116-128. Chambers, H.L. 1962. Experimental studies in Pycnanthemum (Labiatae). Am. J. Bot. 49: 674. Chambers, H.L. 1993. Chromosome survey and analysis of artificial hybrids in Pycnanthemum. Castanea 58: 197-208. Chambers, H.L. and K.L. Chambers. 1971. Artificial and natural hybrids in Pycnanthemum (Labiatae). Brittonia 23: 71-88. Crins, W.J. 1989. Status of the Hoary Mountain Mint, Pycnanthemum incanum (Lamiaceae), in Canada. Canadian Field-Naturalist 103: 283-286. Eickholt, T.H., and R.H. Box. 1965. Toxicities of peppermint and Pycnanthemum albescens oils, fam. Labiateae. J. Pharm. Sci. 54: 1071-1072. Faber-Langendoen, D. and P.F. Maycock. 1987. Composition and soil-environment analysis of prairies on Wapole Island, southwestern Ontario. Can. J. Bot. 65: 2410-2419. Gleason, H.A. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. 2nd ed. New York Botanical Garden, New York. Gleason, H.A. and A. Cronquist. 1963. Manual of vascular plants of northeastern United States and adjacent Canada. D. Van Nostrand Co. Inc., Princeton, NJ. Grant, E. and C. Epling. 1943. A study of Pycnanthemum. Univ. Calif. Pub. Bot. 20: 195-240, Univ. Calif. Press, California. Gray, A. 1848. A manual of the botany of the northern United States. James Monroe and Co., Boston. New Jersey Natural Heritage Program. Element global ranking form for Pycnanthemum clinopodioides. New Jersey Heritage Program, Trenton, New Jersey. Parker, I.M., S.K. Mertens and D.W. Schemske. 1993. Distribution of seven native and two exotic plants in a tallgrass prairie in southeastern Wisconsin: The importance of human disturbance. Am. Mid. Nat. 130: 43-55. Pellett, F.C. 1947. Mountain mint. American Bee Journal. 87: 172- 173. Pellett. F.C. 1950. Mountain mint, a new source of essential oil. American Bee Journal. 90: 66-67. Snyder, D. In Press. Additions, range extensions, reinstatements, and relocations in the New Jersey flora. Bartonia. Sorensen, P.D., and P.A. Matekaitis. 1981. A lemon-scented Pycnanthemum (Lamiaceae). Rhodora 83: 145-146.