The Vascular Plants Technical Committee dates to the organization of the Survey in 1979, and produced "Chapter 1 - Plants" for the 1985 Species of Special Concern in Pennsylvania publication. Its membership includes botanists from colleges and universities, natural history museums, conservation organizations and state and federal agencies. Following the passage of P.L. 597, No. 170 - The Wild Resource Conservation Act, and during the development of the implementing regulations, Title 25, Chapter 82 - Conservation of Pennsylvania Native Wild Plants, the VPTC has provided scientific input to DER Bureau of Forestry. An annual review session has been held each year to recommend additions to or changes in the status of plants classified as extirpated, endangered, threatened, or rare under the regulations. In addition, other policy matters affecting enforcement of the regulations has been addressed. The Vascular Plants Technical Committee also provides an important forum for exchange of information among botanists working in the state.
photograph courtesy of Merlin Benner
The Vascular Plants Technical Committee members are:
- Chris Hardy, committee chair
- James Bissell
- Tim Block
- Rebecca Bowen
- Emilee Boyer
- Eric Burkhart
- Allison Cusick
- Janet Ebert
- Amy Faivre
- Chris Firestone
- Carrie Gilbert
- Steve Grund
- Jack Holt
- Bonnie Isaac
- Joe Isaac
- Ken Klemow
- Larry Klotz
- Wesley Knapp
- John Kunsman
- Carol Loeffler
- Rick Mellon
- April Moore
- Susan Munch
- Ann Rhoads
- Paul Teese
- Robert Whyte
- Charles (Chuck) Williams
Pennsylvania Vascular Plants
VASCULAR PLANTS: REVIEW OF STATUS IN PENNSYLVANIA
Sue A. Thompson
Carnegie Museum of Natural History
INTRODUCTION
Pennsylvania has a diverse vascular flora coupled with a long history of botanical work within the state dating from the 18th century. A variety of habitats and the occurrence of several physiographic provinces contribute to Pennsylvania's floristic diversity. Habitats range from freshwater tidal marshes to limestone barrens, and northern and southern forest types both occur within the state.
Seminal works on vascular plants in Pennsylvania include the Flora of Pennsylvania (Porter 1903), Wild Flowers of Western Pennsylvania and the Upper Ohio Basin (Jennings and Avinoff 1953), and Atlas of the Flora of Pennsylvania (Wherry et al. 1979). Given the age of Porter's work and the fact that Jennings and Avinoff's publication included only western Pennsylvania, the major reference work on the flora of the state was, until recently, the atlas by Wherry et al. (1979).
Initiated in the 1930s and based on over 250,000 herbarium specimens, this atlas claimed to be complete, stating ". . .when a particular species is not shown on our distribution maps, it may be reasonably supposed that it does not occur there. . ." (Wherry et al. 1979:vii). However, many years elapsed between the start of this project and publication of the atlas in 1979, and during this period thousands of additional specimens documenting new distributions of Pennsylvania plants were collected (e.g., Thompson et al. 1989).
Much of this new distributional data was incorporated into a revised atlas, The Vascular Flora of Pennsylvania: Annotated Checklist and Atlas published in 1993 (Rhoads and Klein 1993), which also incorporated taxonomic and nomenclatural changes since the 1979 atlas. This "new atlas" maps 3,318 taxa of vascular plants in Pennsylvania, including both introduced and native species, and is now the major reference on the Pennsylvania flora.
Although published in 1993, the new atlas is already out-of-date. Since its publication, more than 20 species have been added as new to Pennsylvania, including both native and exotic plants, and many new distribution records within the state have been reported (e.g., Cusick and Thompson 1994, Isaac and Isaac 1997, Naczi and Thieret 1996). The vascular plant flora of Pennsylvania is dynamic and always changing, and thus both inventory and monitoring of the state's flora must be on going.
STATUS OF VASCULAR PLANTS
Native plants comprise slightly less than 63% of the vascular flora of Pennsylvania. Of these native taxa, approximately 30% are currently listed as plants of special concern (Fig. 1). More than 5% (116) of native plant species are believed to be extirpated in Pennsylvania, and an additional 20% are classified as Endangered (288), Threatened (80), rare (52), or vulnerable (3) (Appendix 1). Another 93 species are currently classified as undetermined, pending assignment to a specific status. The figure of 30% does not include the approximately 135 species which were under review as of July 1997 by the Vascular Plant Technical Committee for listing as species of special concern.
Thirty-seven Pennsylvania plant species are listed as Globally Rare (G3 rank), Threatened (G2 rank), or Endangered (G1 rank) (Pennsylvania Natural Diversity Inventory (PNDI). Two species which occurred in Pennsylvania, Schweinitz's waterweed (Elodea schweinitzii) and Nuttall's mud-flower (Micranthemum micranthemoides), are considered to be extinct throughout their ranges (Rhoads and Klein 1993).
Fig. 1 Status of vascular plants native to
Pennsylvania.
The high number of Pennsylvania Endangered and Threatened plants may be attributable to the geographic position of Pennsylvania straddling a number of physiographic regions and the diversity of habitats found in the state. Seventy-seven percent of Endangered and Threatened plants in Pennsylvania are at the edge of their geographic range (Walck 1996). Although water-dependent habitats occupy only about 2% of the land surface in Pennsylvania, 57% of Endangered and Threatened plant species grow in these habitats (Walck 1996). Not surprisingly, families with the largest number of Pennsylvania Endangered and Threatened plants, the sedges (Cyperaceae), grasses (Poaceae), and composites (Asteraceae), are the families with the greatest number of species in Pennsylvania.
EXOTICS
More than any other group of organisms in Pennsylvania, the state's native flora has been impacted by the establishment of alien species. Over 37% of the vascular plant species now growing within the borders of Pennsylvania are not native. This figure is much higher in some groups, such as the mustard family (Brassicaceae), for which almost 80% of the species in Pennsylvania are introduced.
Exotic species range from noxious weeds (Appendix 2), such as purple loosestrife (Lythrum salicaria) and mile-a-minute weed (Polygonum perfoliatum), to plants that many people enjoy as Pennsylvania wildflowers, such as ox-eye daisy (Chrysanthemum leucanthemum) and even a species of orchid (Epipactis helleborine). Exotic plant
Species are a significant threat to the native flora and are discussed in that context below.
THREATS
Threats to the vascular flora of Pennsylvania are of 2 kinds: those threats that directly affect plants and their habitats and threats that impede study of the flora. Historically, the greatest threats to the native Pennsylvania flora have been land use practices that alter natural habitats, including deforestation, urban and suburban expansion, road-building through natural habitats, and draining of wetlands.
Colonization of disturbed areas and native habitats by invasive, introduced species such as garlic mustard (Alliaria petiolata) and multiflora rose (Rosa multiflora) is an increasing threat. Introduced pests and diseases, including the gypsy moth (Lymantria dispar) and Dutch elm disease, have altered the composition of many forests in Pennsylvania, especially those already weakened by other threats, such as white-tailed deer (Odocoileus virginianus). Over-browsing by white-tailed deer has resulted in a decrease in species diversity, changes in forest structure in many parts of Pennsylvania, and a threat to more than 20 species of Endangered and Threatened wildflowers (Rhoads 1996). Public education about the benefits of biodiversity is key to campaigns to ameliorate many of these direct threats. As more and more people enjoy Pennsylvania's natural resources, recreational use is also negatively impacting native habitats.
In addition to direct threats, native plant species are threatened by the lack of expertise and resources to address issues important to their preservation. There is a critical shortage of trained plant systematists and their support personnel not only in Pennsylvania, but worldwide. A recent survey found only 940 systematic biologists (including botanists and zoologists) employed by Ph.D.-granting universities in the entire United States (Anonymous 1994). Currently no Pennsylvania university maintains a recognized doctorate program in plant systematics. Efforts are under way at both the national and state level to develop programs to recruit, educate, and train systematists and other biodiversity specialists, but meaningful post-graduate employment may still remain a problem.
The lack of employment opportunities for trained systematists stems in part from a lack of infrastructure support for collections-based resources and the types of field projects they conduct. Appropriate scientific infrastructure is necessary to effective data gathering that results in informed decision making. Like elsewhere in the world, Pennsylvania suffers from a lack of adequate funds dedicated to these issues.
Integrated studies of the flora of Pennsylvania are hampered by the historic division of plant studies among major herbaria in the eastern, western, and central regions, and the lack of coordination among conservation organizations. This poor statewide coordination between and among regions, state agencies, and private institutions is improving, but still hinders comprehensive and integrated studies of the state's flora.
INVENTORYING AND MONITORING
For the past several years, the vascular plant technical committee of the Pennsylvania Biological Survey has concentrated on developing and refining a checklist of plant species of special concern in Pennsylvania and assigning an appropriate status to each species. Further refinement of this list is on going, including a systematic assessment of all Pennsylvania native plant species to determine if any candidate species have been overlooked. This project resulted in approximately 135 additional species targeted for review as species of special concern.
Discovery of new localities and monitoring of known populations of special concern species is on going and involves staff of Pennsylvania Natural Diversity Inventory, the Western Pennsylvania Conservancy, and The Nature Conservancy, as well as botanists at many other institutions throughout the state. Staff at the Carnegie Museum of Natural History herbarium have targeted under-collected areas of the state for more intensive fieldwork on all vascular plants, not just species of special concern.
The Pennsylvania Flora Project, based at Morris Arboretum in Philadelphia, has been particularly active in recent years with the publication of the new atlas (Rhoads and Klein 1993) and plans to produce a field manual to the vascular flora of Pennsylvania by the end of the millennium (Rhoads and Block 1997; A. F. Rhoads, pers. comm.). In conjunction with the Academy of Natural Sciences in Philadelphia, they sponsor an annual Pennsylvania Flora Intern, housed at the Academy, and have already employed several students in this position.
Educational projects, including the development of materials on native wild plants, are under way by the Carnegie Museum of Natural History botany and education staffs. Preparation of information on potentially invasive species and on the use of native plants for landscaping is under way at the Bureau of Forestry.
COLLECTIONS, DATABASES, AND GAPS IN INFORMATION
Many of the vascular plants of selected areas of Pennsylvania have been extensively documented with probably over 400,000 herbarium specimens (including duplicates) currently available (Thorne et al. 1995). Most of these specimens are housed in herbaria at 3 Pennsylvania institutions (codes follow Holmgren et al. 1990): (1) the Academy of Natural Sciences, Philadelphia (PH) (including the herbarium of the University of Pennsylvania (PENN) which is housed at PH); (2) the Carnegie Museum of Natural History, Pittsburgh (CM); and (3) The Pennsylvania State University, University Park (PAC). The CM herbarium alone housed over 135,000 specimens of vascular plants collected in Pennsylvania as of July 1997.
In addition to the above 3 major repositories for Pennsylvania plant specimens, 16 other herbaria with vascular plants, associated mostly with colleges and universities, are located in Pennsylvania (Holmgren et al. 1990). Not all specimens of Pennsylvania plants are in Pennsylvania institutions, and important collections of especially older material are deposited at places such as the Field Museum (F) in Chicago; Gray Herbarium (GH) at Harvard University; New York Botanical Garden (NY) Bronx; and the US National Herbarium (US), Washington, D.C. Smaller collections at institutions in states bordering Pennsylvania (e.g., Youngstown State University (YUO) in Ohio and others) contain significant collections of Pennsylvania vascular plants.
While many of the specimens of Pennsylvania vascular plants represent historical collections, new material is continually being prepared and added to herbaria, especially those in Pennsylvania. For example, by July 1997 the CM herbarium had added almost 20,000 specimens collected in Pennsylvania since publication of the revised atlas.
The major primary database of Pennsylvania vascular plants is the CM herbarium database, which contains label data for all Pennsylvania specimens at CM. Data from new specimens are continually added and specimen data records are updated with changes in identification or nomenclature. Secondary databases (e.g., those which do not have a direct continuing link to the specimens on which data records are based) on Pennsylvania vascular plants include the Pennsylvania Flora database at Morris Arboretum, which contains records for all taxa occurring in Pennsylvania, and the Pennsylvania Natural Diversity Inventory database, which focuses on plant species of special conservation concern and contains records based on field surveys in addition to specimen-based records.
Knowledge of the vascular plants of Pennsylvania is adequate, and even relatively good for some taxa and areas of the state, at the basic floristic level. However, beyond alpha-level checklists, distribution maps, and some notions of which species are of special conservation interest, little is known about the plants of Pennsylvania. Species-specific issues such as genetic diversity, variation, ecology, habitat requirements, life history, or management needs remain unknown for the majority of vascular plants in Pennsylvania. Even in terms of basic floristics, there are still major gaps in our knowledge, which fall into 3 general categories: (1) spatial, (2) taxonomic, and (3) temporal.
Spatial: The long history of botanical fieldwork in Pennsylvania has resulted in a large number of specimens, which gives the impression that the state has been well collected. Unfortunately, this is not the case. A comprehensive field survey which systematically documented plants throughout the state has never been conducted. Staff at the 3 major herbaria tended to collect specimens near their institutions, and early botanists did not venture much into areas considered to be within the "territory" of the other institutions (W.E. Buker, pers. commun.). The CM herbarium, for example, has over 14,000 specimens from Allegheny County, where it is located, but just slightly more than 100 specimens from Columbia County in northeastern Pennsylvania. Until recent years, documentation of the Pennsylvania flora has been primarily on an ad hoc basis, and to this day significant areas of Pennsylvania remain botanical terra incognita.
Areas of the state that are poorly represented by botanical collections include the northern tier of counties, the extreme southwestern corner, counties along the southern border, regions that are remote from roads, and miscellaneous other areas throughout the state. In only 7 days of fieldwork in June 1990 and June 1994, botanists documented 80 species (in 29 genera) new to Bradford County, including 2 species also new to the state (Naczi and Thieret 1996). Another species new to Pennsylvania (Myosotis macrosperma) was collected several times since 1995 in 3 different counties along Pennsylvania's southern border, and the death-camas lily (Zigadenus elegans var. glaucus) was discovered in a relatively inaccessible area of Huntingdon County in 1994 (Isaac and Isaac 1997).
Taxonomic: The problem of taxonomically unresolved and difficult groups of plants is not unique to Pennsylvania. The status in Pennsylvania of notoriously difficult genera, such as Rubus (blackberries, raspberries, and dewberries), Crataegus (hawthorns), and Panicum (panic-grass), is a continuing problem, which will not be resolved by studies restricted to only Pennsylvania specimens. Resolution of the number of species of such genera in Pennsylvania must await taxonomic revisions of these groups.
The problem of taxonomic difficulties extends as well to proper curation of the hundreds of thousands of Pennsylvania specimens already in herbaria and the lack of botanical expertise to undertake this task. Often, "new" discoveries have been made based on herbarium specimens, which had been (1) overlooked, (2) not well curated, or (3) not correctly identified. In 1994, for example, 2 plant species were reported as "new" to Pennsylvania based on specimens collected by John Miller in the early 1900s and maintained by the Erie Historical Society and Planetarium until 1988 when they were donated to CM (Cusick and Thompson 1994). Another species reported for the first time in Pennsylvania in that same paper (Cusick and Thompson 1994) was a result of specimens which had been misidentified and were redetermined by the taxonomic expert in that group of plants.
Taxonomic problems and issues affect information on Pennsylvania vascular plants at all levels. In addition to supporting increased funding for taxonomic research and educational initiatives, increased curatorial attention to the many specimens already in hand is necessary.
Temporal: The atlas by Rhoads and Klein (1993) maps plant distributions in Pennsylvania based on specimens collected over many years, but it does not give any indication of year in which the specimens documenting the distribution maps were collected. For many species, this results in misleading distribution maps of current occurrences. Although the overall historical distribution may be known, the present distribution of the vascular plants of Pennsylvania, outside of a handful of Rare and Endangered species, remains unknown. The small-headed sunflower (Helianthus microcephalus) is presented in the 1993 atlas as occurring in 16 counties, based on over 68 specimens (Fig. 2). Of those specimens, however, only 4 were collected after 1969, the most recent one in 1987! Similarly, over 61% of the known Pennsylvania specimens of fire pink (Silene virginica), a showy plant that would attract botanists' attention, were collected prior to 1950.
Clearly there are major gaps in current knowledge on the distribution of vascular plant species in Pennsylvania. Plant inventory may be mostly complete, but
Fig 2. Distribution of small-headed
sunflower (Helianthus microcephalus)
in Pennsylvania based on all specimens (upper
map) versus distribution
of that same species based only on specimens collected after 1969
(lower map).
monitoring is needed to provide current information on most of the plant species in Pennsylvania. The inability to adequately monitor the state's flora can be attributed at least in part to lack of sufficient botanical expertise within the state and a decline in fieldwork focused on Pennsylvania. Until recently, the CM herbarium showed a dramatic decrease from the 1950s through the 1980s in the number of Pennsylvania plant specimens added to the collection (Fig. 3). Systematic field surveys of all areas and taxa are needed to address this problem.
In addition to lack of information on current plant distribution in Pennsylvania, there may also be problems associated with uneven data on a phenological basis. Collections of plant specimens are concentrated in the months from June to September with marked decreases in the number of specimens collected in early spring and late fall (CM Pennsylvania Plant Database). The occurrence and distribution of species with phenologies restricted to early spring and late fall may be skewed, and additional fieldwork is needed during early spring and late fall.
Fig. 3. Number of Pennsylvania plant
specimens in the Carnegie Museum of
Natural History herbarium by year of collection.
ACKNOWLEDGMENTS
I thank the many botanists from throughout the state who responded to my request for input on the status of our knowledge of Pennsylvania vascular plants. Funding from the Wild Resource Conservation Fund has been essential to many projects on vascular plants in Pennsylvania, especially those targeted as species of special concern.
REFERENCES
Anonymous. 1994. Systematics agenda 2000: charting the biosphere, Technical Report. Systematics Agenda 2000, [New York].
Cusick, A. W., and S. A. Thompson. 1994. Noteworthy collections from Pennsylvania. Bartonia 58:69-73.
Holmgren, P. K., N. H. Holmgren, and L. C. Barnett. 1990. Index herbariorum. Part I: The herbaria of the world, Eighth ed. Regnum Vegetabile 120:1-693.
Isaac, B. L., and J. A. Isaac. 1997. Noteworthy collections: Pennsylvania. Castanea 62:131-132.
Jennings, O. E., and A. Avinoff. 1953. Wild flowers of western Pennsylvania and the Upper Ohio Basin. Univ. Pittsburgh Press, Pittsburgh, Pa. 2 vols.
Naczi, R. F. C., and J. W. Thieret. 1996. Additions to the flora of Bradford County, Pennsylvania. Bartonia 59:81-85.
Porter, T. C. 1903. Flora of Pennsylvania. Ginn and Co., Boston.
Rhoads, A. F. 1996. Something is missing. Pennsylvania Game News 16:10-13.
Rhoads, A. F., and T. A. Block. 1997. The Pennsylvania flora project: history and ongoing work of the Botany Department at the Morris Arboretum [abstract]. Am. J. Botany, Supplement 84:253.
Rhoads, A. F., and W. M. Klein, Jr. 1993. The vascular flora of Pennsylvania: annotated checklist and atlas. American Philosophical Society, Philadelphia, Pa. 636pp.
Thompson, S. A., W. E. Buker, and M. Macdonald. 1989. Notes on the distribution of Pennsylvania plants based on specimens in the Carnegie Museum of Natural History herbarium. Carnegie Mus. Nat. Hist. Spec. Publ. 14:1-55.
Thorne, S. G., K. C. Kim, K. C. Steiner (project co-directors), and B. J. McGuinness (ed.). 1995. A heritage for the 21st century: conserving Pennsylvania's native biological diversity. Pennsylvania Fish & Boat Comm., Harrisburg, Pa. 72pp.
Walck, J. L. 1996. Distribution, life forms, taxonomic categories, and habitats of the Endangered and Threatened vascular plants in Pennsylvania: A summary. Bartonia 59:49-54.
Wherry, E. T., J. M. Fogg, Jr., and H. A. Wahl. 1979. Atlas of the flora of Pennsylvania. Univ. Pennsylvania, Morris Arboretum, Philadelphia.
Appendix 1
Vulnerable, Rare, Threatened, Endangered, and Extirpated Vascular Plants of
Pennsylvania as Listed by the Pennsylvania Biological Survey (March 1997).
Legislative Authority: Title 25 Chapter 82, Conservation of Pennsylvania Native Wild Plants, effective January 1, 1988; amended June 18, 1993.
Responsible Agency: Department of Conservation and Natural Resources.
Pennsylvania Vulnerable - Plant species which are in danger of population decline within this Commonwealth because of their beauty, economic value, use as a cultivar, or other factors which indicate that persons may seek to remove these species from their native habitats.
Pennsylvania Rare - Plant species which are uncommon within this Commonwealth because they may be found in restricted geographic areas or in low numbers throughout this Commonwealth.
Pennsylvania Threatened - Plant species which may become Endangered throughout most or all of their natural range within this Commonwealth, if critical habitat is not maintained to prevent their further decline in this Commonwealth, or if the species is greatly exploited by man.
Pennsylvania Endangered - Plant species which are in danger of extinction throughout most or all of their natural range within this Commonwealth, if critical habitat is not maintained or if the species is greatly exploited by man. This classification also includes populations of plant species that have been classified as Pennsylvania Extirpated, but which subsequently are found to exist in this Commonwealth.
Pennsylvania Extirpated - Plant species believed by the Department [of Conservation and Natural Resources] to be extinct within this Commonwealth. These plants may or may not exist outside the Commonwealth.
Pennsylvania Vulnerable
| COMMON NAME | SCIENTIFIC NAME |
| large yellow lady's slipper | Cypripedium pubescens |
| goldenseal | Hydrastis canadensis |
| ginseng | Panax quinquefolium |
Pennsylvania Rare
| COMMON NAME | SCIENTIFIC NAME |
| waterhemp ragweed | Amaranthus cannabinus |
| bog-rosemary | Andromeda polifolia |
| shale-barren pussytoes | Antennaria virginica |
| puttyroot | Aplectrum hyemale |
| lobed spleenwort | Asplenium pinnatifidum |
| eastern baccharis | Baccharis halimifolia |
| American sea-rocket | Cakile edentula |
| brown sedge | Carex buxbaumii |
| soft-leaved sedge | Carex disperma |
| slender sedge | Carex lasiocarpa |
| bog sedge | Carex paupercula |
| mountain bugbane | Cimicifuga americana |
| Engelmann's flatsedge | Cyperus engelmannii |
| Schweinitz's flatsedge | Cyperus schweinitzii |
| small waterwort | Elatine minima |
| capitate spike-rush | Eleocharis olivacea |
| creeping snowberry | Gaultheria hispidual |
| thread rush | Juncus filiformis |
| Coville's rush | Juncus gymnocarpuc |
| common labrador-tea | Ledum groenlandicum |
| wild blue lupine | Lupinus perennis |
| Hartford fern | Lygodium palmatum |
| umbrella magnolia | Magnolia tripetala |
| Bayard's malaxis | Malaxis bayardii |
| minniebush | Menziesia pilosa |
| prickly-pear cactus | Opuntia humifusa |
| golden club | Orontium aquaticum |
| fog-fruit | Phyla lanceolata |
| Illinois pondweed | Potamogeton illinoensis |
| flat-leaved pondweed | Potamogeton robbinsii |
| flat-stem pondweed | Potamogeton zosteriformis |
| sand cherry | Prunus pumila |
| buffalo nut | Pyrularia pubera |
| white water-crowfoot | Ranunculus trichohyllus |
| tooth-cup | Rotala ramosior |
| subulate arrow-head | Sagittaria subulata |
| lettice saxofrage | Saxifraga micranthidifolia |
| seaside bluestem | Schizachyrium scoparium var. littorale |
| river bullrush | Scirpus fluviatilis |
| Allegheny stonecrop | Sedum telephioides |
| plain ragwort | Senecio anonymus |
| Tennessee golden-rod | Solidago roanesis |
| sand dropseed | Sporobolus cryptandrus |
| crainfly orchid | Tipularia discolor |
| Carolina tassel-rue | Trautvetteria caroliniens |
| snow trillium | Trillium nivale |
| purple bladderwort | Utricularia purpurea |
| mountain bellwort | Uvularia puberula |
| highbush cranberry | Viburnum trilobum |
| bog mat | Wolffiella gladiata |
| yellow-eyed grass | Xyris montana |
| Indian wild rice | Zizania aquatica |
Pennsylvania Endangered
| COMMON NAME | SCIENTIFIC NAME |
| white monkshood | Aconitum reclinatum |
| sweet flag | Acorus americanus |
| small-flowered false foxglove | Agalinis paupercula |
| colic-root | Aletris farinosa |
| broad-leaved water plantain | Alisma plantago-aquatica var. americana |
| mountain alder | Alnus viridis ssp. crispa |
| oblong-fruited serviceberry | Amelanchier bartramiana |
| low serviceberry | Amelanchier humilis |
| coastal plain serviceberry | Amelanchier obovalis |
| roundleaf serviceberry | Amelanchier sanguinea |
| long-fruited anemone | Anemone cylindrica |
| single-head pussytoes | Antennaria solitaria |
| hairy rock-cress | Arabis hirsuta |
| Missouri rock-cress | Arabis missouriensis |
| swamp-pink | Arethusa bulbosa |
| leopard's-bane | Arnica acaulis |
| beach wormwood | Artemisia campestris ssp. caudata |
| white milkweed | Asclepias variegata |
| Bradley's spleenwort | Asplenium bradleyi |
| black-stalked spleenwort | splenium resiliens |
| rush aster | Aster borealis |
| bog aster | Aster nemoralis |
| narrow-leaved white-topped aster | Aster solidagineus |
| low showy aster | Aster spectabilis |
| Cooper's milk-vetch | Astragalus neglectus |
| swamp beggar-ticks | Bidens bidentoides |
| aster-like boltonia | Boltonia asteroides |
| wild hyacinth | Camassia scilloides |
| awned sedge | Carex atherodes |
| golden-fruited sedge | Carex aurea |
| Bebb's sedge | Carex bebbii |
| Bicknell's sedge | Carex bicknellii |
| bull sedge | Carex bullata |
| Carey's sedge | Carex careyana |
| Crawford's sedge | Carex crawfordii |
| short hair sedge | Carex crinita var. brevicrinis |
| northeastern sedge | Carex cryptolepis |
| ebony sedge | Carex eburnea |
| handsome sedge | Carex formosa |
| elk sedge | Carex garberi |
| Geyer's sedge | Carex geyeri |
| Mead's sedge | Carex meadii |
| Mitchell's sedge | Carex mitchelliana |
| few-flowered sedge | Carex pauciflora |
| cyperus-like sedge | Carex pseudocyperus |
| backward sedge | Carex retrorsa |
| Richardson's sedge | Carex richardsonii |
| Schweinitz's sedge | Carex schweinitzii |
| Atlantic sedge | Carex sterilis |
| cattail sedge | Carex typhina |
| green sedge | Carex viridula |
| mouse-ear chickweed | Cerastium arvense var. villosissimum |
| slender sea-oats | Chasmanthium laxum |
| Fogg's goosefoot | Chenopodium foggii |
| green-and-gold | Chrysogonum virginianum |
| Maryland golden aster | Chrysopsis mariana |
| horrible thistle | Cirsium horridulum |
| twig rush | Cladium mariscoides |
| vase-vine leather-flower | Clematis viorna |
| mountain pepper-bush | Clethra acuminata |
| butterfly-pea | Clitoria mariana |
| hemlock-parsley | Conioselinum chinense |
| Wister's coral-root | Corallorhiza wisteriana |
| golden corydalis | Corydalis aurea |
| slender rock-brake | Cryptogramma stelleri |
| Fraser's sedge | Cymophyllus fraseri |
| smooth swallow-wort | Cynanchum laeve |
| umbrella flatsedge | Cyperus diandrus |
| Houghton's flatsedge | Cyperus houghtonii |
| reflexed flatsedge | Cyperus refractus |
| small yellow lady's-slipper | Cypripedium parviflorum |
| Laurentian bladder fern | Cystopteris laurentiana |
| tall larkspur | Delphinium exaltatum |
| American beakgrain | Diarrhena obovata |
| wild bleeding-hearts | Dicentra eximia |
| common shooting-star | Dodecatheon meadia |
| mountain wood fern | Dryopteris campyloptera |
| log fern | Dryopteris celsa |
| Walter's barnyard-grass | Echinochloa walteri |
| long-stemmed water-wort | Elatine americana |
| capitate spike-rush | Eleocharis caribaea |
| flat-stemmed spike-rush | Eleocharis compressa |
| slender spike-rush | Eleocharis elliptica |
| spike-rush | Eleocharis obtusa var. peasei |
| dwarf spike-rush | Eleocharis parvula |
| few-flowered spike-rush | Eleocharis pauciflora var. fernaldii |
| four-angled spike-rush | Eleocharis quadrangulata |
| beaked spike-rush | Eleocharis rostellata |
| slender spike-rush | Eleocharis tenuis var. verrucosa |
| elephant's foot | Elephantopus carolinianus |
| downey willow-herb | Epilobium strictum |
| variegated horsetail | Equisetum variegatum |
| scouring rush | Equisetum ferrissii |
| slender cotton-grass | Eriophorum gracile |
| rough cotton-grass | Eriophorum tenellum |
| wild ipecac | Euphorbia ipecacuanhae |
| blunt-leaved spurge | Euphorbia obtusata |
| glade spurge | Euphorbia purpurea |
| cluster fescue | Festuca paradoxa |
| American columbo | Frasera caroliniensis |
| pumpkin ash | Fraxinus profunda |
| Labrador marsh bedstraw | Galium labradoricum |
| box huckleberry | Gaylussacia brachycera |
| dwarf huckleberry | Gaylussacia dumosa |
| soapwort gentian | Gentiana saponaria |
| striped gentian | Gentiana villosa |
| cranesbill | Geranium bicknellii |
| blunt manna-grass | Glyceria obtusa |
| golden-pert | Gratiola aurea |
| Appalachian oak fern | Gymnocarpium appalachianum |
| Bicknell's hoary rockrose | Helianthemum bicknellii |
| common hemicarpa | Hemicarpha micrantha |
| multiflowered mud-plantain | Heteranthera multiflora |
| Maryland hawkweed | Hieracium traillii |
| vanilla sweet-grass | Hierochloe odorata |
| rock clubmoss | Huperzia porophila |
| large-leafed water-leaf | Hydrophyllum macrophyllum |
| purple rocket | Iodanthus pinnatifidus |
| crested dwarf iris | Iris cristata |
| slender blue iris | Iris prismatica |
| dwarf iris | Iris verna |
| Virginia blue flag | Iris virginica |
| small-whorled pogonia | Isotria medeoloides |
| short-fruited rush | Juncus brachycarpus |
| forked rush | Juncus dichotomus |
| bayonet rush | Juncus militaris |
| scirpus-like rush | Juncus scirpoides |
| Torrey's rush | Juncus torreyi |
| marsh pea | Lathyrus palustris |
| narrowleaf bush clover | Lespedeza angustifolia |
| lovage | Ligusticum canadense |
| sandplain wild flax | Linum intercursum |
| grooved yellow flax | Linum sulcatum |
| southern twayblade | Listera australis |
| heart-leaved twayblade | Listera cordata |
| kidney-leaved twayblade | Listera smallii |
| hispid gromwell | Lithospermum caroliniense |
| American gromwell | Lithospermum latifolium |
| brook lobelia | Lobelia kalmii |
| downy lobelia | Lobelia puberula |
| hairy honeysuckle | Lonicera hirsuta |
| swamp fly honeysuckle | Lonicera oblongifolia |
| mountain fly honeysuckle | Lonicera villosa |
| upright primrose-willow | Ludwigia decurrens |
| false loosestrife seedbox | Ludwigia polycarpa |
| wood-rush | Luzula bulbosa |
| foxtail clubmoss | Lycopodiella alopecuroides |
| taper-leaved bugle-weed | Lycopus rubellus |
| stagger-bush | Lyonia mariana |
| winged loosestrife | Lythrum alatum |
| white adder's-mouth | Malaxis brachypoda |
| large-flowered marshallia | Marshallia grandiflora |
| oblique milkvine | Matelea obliqua |
| heart-leafed meehania | Meehania cordata |
| Beck's water-marigold | Megalodonta beckii |
| naked bishop's-cap | Mitella nuda |
| spotted bee-balm | Monarda punctata |
| Chamisso's miner's-lettuce | Montia chamissoi |
| false dropseed muhly | Muhlenbergia uniflora |
| northern water-milfoil | Myriophyllum exalbescens |
| Farwell's water-milfoil | Myriophyllum farwellii |
| broad-leaved water-milfoil | Myriophyllum heterophyllum |
| whorled water-milfoil | Myriophyllum verticillatum |
| holly-leaved naiad | Najas marina |
| American lotus | Nelumbo lutea |
| false gromwell | Onosmodium hispidissimum |
| limestone adder's-tongue | Ophioglossum engelmannii |
| slender mountain-ricegrass | Oryzopsis pungens |
| southern sea-beach panic-grass | Panicum amarum var. amarulum |
| annulus panic-grass | Panicum annulum |
| panic-grass | Panicum commonsianum var. euchlamydeum |
| panic-grass | Panicum laxiflorum |
| shining panic-grass | Panicum lucidum |
| velvety panic-grass | Panicum scoparium |
| acuminate dichanthelium | Panicum spretum |
| slender panic-grass | Panicum xanthophysum |
| Carolina grass-of-parnassus | Parnassia glauca |
| forked chickweed | Paronychia fastigiata var. nuttallii |
| passion-flower | Passiflora lutea |
| Canby's mountain-lover | Paxistima canbyi |
| swamp lousewort | Pedicularis lanceolata |
| mountain phlox | Phlox ovata |
| downy phlox | Phlox pilosa |
| moss pink | Phlox subulata ssp. brittonii |
| Carolina leaf-flower | Phyllanthus caroliniensis |
| Virginia ground-cherry | Physalis virginiana |
| leafy white orchid | Platanthera dilatata |
| Hooker's orchid | Platanthera hookeri |
| leafy northern green orchid | Platanthera hyperborea |
| shrubby camphor-weed | Pluchea odorata |
| autumn bluegrass | Poa autumnalis |
| Jacob's-ladder | Polemonium van-bruntiae |
| cross-leaved milkwort | Polygala cruciata |
| Curtis's milkwort | Polygala curtissii |
| pink milkwort | Polygala incarnata |
| bitter milkwort | Polygala polygama |
| eastern jointweed | Polygonella articulata |
| Carey's smartweed | Polygonum careyi |
| swamp smartweed | Polygonum setaceum var. interjectum |
| Braun's holly fern | Polystichum braunii |
| balsam poplar | Populus balsamifera |
| Fries' pondweed | Potamogeton friesii |
| grassy pondweed | Potamogeton gramineus |
| Hill's pondweed | Potamogeton hillii |
| Oakes' pondweed | Potamogeton oakesianus |
| blunt-leaved pondweed | Potamogeton obtusifolius |
| white-stemmed pondweed | Potamogeton praelongus |
| spotted pondweed | Potamogeton pulcher |
| narrow-leaved pondweed | Potamogeton strictifolius |
| Tennessee pondweed | Potamogeton tennesseensis |
| Vasey's pondweed | Potamogeton vaseyi |
| shrubby cinquefoil | Potentilla fruticosa |
| bushy cinquefoil | Potentilla paradoxa |
| three-toothed cinquefoil | Potentilla tridentata |
| rattlesnake-root | Prenanthes crepidinea |
| beach plum | Prunus maritima |
| southern mountain-mint | Pycnanthemum pycnanthemoides |
| Torrey's mountain-mint | Pycnanthemum torrei |
| southern red oak | Quercus falcata |
| willow oak | Quercus phellos |
| Shumard's oak | Quercus shumardii |
| tufted buttercup | Ranunculus fascicularis |
| low spearwort | Ranunculus pusillus |
| lanceolate buckthorn | Rhamnus lanceolata |
| Maryland meadow-beauty | Rhexia mariana |
| dwarf azalea | Rhododendron atlanticum |
| capillary beaked-rush | Rhynchospora capillacea |
| bristly black currant | Ribes lacustre |
| Missouri gooseberry | Ribes missouriense |
| sand blackberry | Rubus cuneifolius |
| fringed-leaved petunia | Ruellia humilis |
| long-lobed arrow-head | Sagittaria calycina var. spongiosa |
| hoary willow | Salix candida |
| Carolina willow | Salix caroliniana |
| bog-willow | Salix pedicellaris |
| slender willow | Salix petiolaris |
| pineland pimpernel | Samolus parviflorus |
| pod-grass | Scheuchzeria palustris |
| hard-stemmed bullrush | Scirpus acutus |
| Smith's bullrush | Scirpus smithii |
| Torrey's bullrush | Scirpus torreyi |
| minor nutrush | Scleria minor |
| reticulated nutrush | Scleria reticularis |
| whorled nutrush | Scleria verticillata |
| rock skullcap | Scutellaria saxatilis |
| showy skullcap | Scutellaria serrata |
| roseroot stonecrop | Sedum rosea |
| cat's-paw ragwort | Senecio antennariifolius |
| Canada buffalo-berry | Shepherdia canadensis |
| sida | Sida hermaphrodita |
| eastern blue-eyed grass | Sisyrinchium atlanticum |
| Harris' goldenrod | Solidago arguta var. harrissii |
| Curtis' goldenrod | Solidago curtisii |
| slender goldenrod | Solidago erecta |
| stiff goldenrod | Solidago rigida |
| sticky goldenrod | Solidago spathulata var. racemosa |
| showy mountain-ash | Sorbus decora |
| branching bur-reed | Sparganium androcladum |
| Case's ladies'-tresses | Spiranthes casei |
| October ladies'-tresses | Spiranthes ovalis |
| hooded ladies'-tresses | Spiranthes romanzoffiana |
| spring ladies'-tresses | Spiranthes vernalis |
| rough dropseed | Sporobolus clandestinus |
| prairie dropseed | Sporobolus heterolepis |
| Nuttall's hedge-nettle | Stachys nuttallii |
| white twisted-stalk | Streptopus amplexifolius |
| pencil-flower | Stylosanthes biflora |
| mountain pimpernel | Taenidia montana |
| thick-leaved meadow-rue | Thalictrum coriaceum |
| eared false-foxglove | Tomanthera auriculata |
| Ohio spiderwort | Tradescantia ohiensis |
| blue-curls | Trichostema setaceum |
| Kate's mountain clover | Trifolium virginicum |
| horse-gentian | Triosteum angustifolium |
| nodding pogonia | Triphora trianthophora |
| purple sandgrass | Triplasis purpurea |
| gamma grass | Tripsacum dactyloides |
| narrow false oats | Trisetum spicatum |
| spreading globe flower | Trollius laxus |
| floating bladderwort | Utricularia radiata |
| tawny ironweed | Vernonia glauca |
| possum haw viburnum | Viburnum nudum |
| coast violet | Viola brittoniana |
| prairie violet | Viola pedatifida |
| possum grape | Vitis cinerea var. baileyana |
| sand grape | Vitis rupestris |
| New England grape | Vitis novae-angliae |
| death-camas | Zigadenus elegans var. glaucus |
Pennsylvania Extirpated
| COMMON NAME | SCIENTIFIC NAME |
| two-seeded copperleaf | Acalypha deamii |
| sensitive joint-vetch | Aeschynomene virginica |
| blue-ridge false-foxglove | Agalinis decemloba |
| tall bentgrass | Agrostis altissima |
| bearberry manzanita | Arctostaphylos uva-ursi |
| red milkweed | Asclepias rubra |
| American barberry | Berberis canadensis |
| bluehearts | Buchnera americana |
| crowded sedge | Carex adusta |
| Fernald's hay sedge | Carex aenea |
| Rocky Mountain sedge | Carex backii |
| Barratt's sedge | Carex barrattii |
| creeping sedge | Carex chordorrhiza |
| shore-line sedge | Carex hyalinolepis |
| Sartwell's sedge | Carex sartwellii |
| Atlantic white cedar | Chamaecyparis thyoides |
| slender day-flower | Commelina erecta |
| Virginia day-flower | Commelina virginica |
| pink tickseed | Coreopsis rosea |
| water pigmy-weed | Crassula aquatica |
| elliptical rushfoil | Crotonopsis elliptica |
| northern hound's-tongue | Cynoglossum boreale |
| many-spiked flatsedge | Cyperus polystachyos |
| retrorse flatsedge | Cyperus retrorsus |
| small white lady's-slipper | Cypripedium candidum |
| sessile-leaved tick-trefoil | Desmodium sessilifolium |
| fir clubmoss | Diphasiastrum sabinifolium |
| sea-shore salt-grass | Distichlis spicata |
| Carolina whitlow-grass | Draba reptans |
| smooth coneflower | Echinacea laevigata |
| three-ribbed spike-rush | Eleocharis tricostata |
| long-tubercled spike-rush | Eleocharis tuberculosa |
| Schweinitz's waterweed | Elodea schweinitzii |
| sugarcane plumegrass | Erianthus giganteus |
| ten-angle pipewort | Eriocaulon decangulare |
| Parker's pipewort | Eriocaulon parkeri |
| marsh eryngo | Eryngium aquaticum |
| white thoroughwort | Eupatorium album |
| white-bracted thoroughwort | Eupatorium leucolepis |
| hairy fimbry | Fimbristylis puberula |
| eastern milk-pea | Galactia regularis |
| downy milk-pea | Galactia volubilis |
| yellow gentian | Gentiana alba |
| Elliott's gentian | Gentiana catesbaei |
| lesser fringed gentian | Gentianopsis procera |
| oak fern | Gymnocarpium heterosporum |
| broad-leaved beardgrass | Gymnopogon ambiguus |
| creeping bluets | Hedyotis michauxii |
| swamp sunflower | Helianthus angustifolius |
| little barley | Hordeum pusillum |
| American featherfoil | Hottonia inflata |
| mountain clubmoss | Huperzia selago |
| many-flowered pennywort | Hydrocotyle umbellata |
| creeping St. John's-wort | Hypericum adpressum |
| coppery St. John's-wort | Hypericum denticulatum |
| nits-and-lice | Hypericum drummondii |
| clasping-leaved St. John's-wort | Hypericum gymnanthum |
| St. Peter's-wort | Hypericum stans |
| ink-berry | Ilex glabra |
| Virginia willow | Itea virginica |
| Greene's rush | Juncus greenei |
| junegrass | Koeleria cristata |
| sand-myrtle | Leiophyllum buxifolium |
| little water duckweed | Lemna obscura |
| pale duckweed | Lemna valdiviana |
| tall bushclover | Lespedeza stuevei |
| awl-shaped mudwort | Limosella australis |
| Nuttall's lobelia | Lobelia nuttallii |
| spherical-fruited seedbox | Ludwigia sphaerocarpa |
| Nuttall's mud-flower | Micranthemum micranthemoides |
| short muhly | Muhlenbergia capillaris |
| Virginia false-gromwell | Onosmodium virginianum |
| southeastern adder's tongue | Ophioglossum pycnostichum |
| cloaked panic-grass | Panicum commonsianum var. commonsianu |
| Leiberg's panic-grass | Panicum leibergii |
| American fever-few | Parthenium integrifolium |
| Florida beadgrass | Paspalum floridanum var. glabratum |
| Christmas mistletoe | Phoradendron serotinum |
| black oatgrass | Piptochaetium avenaceum |
| crested yellow orchid | Platanthera cristata |
| prairie white-fringed orchid | Platanthera leucophaea |
| yellow milkwort | Polygala lutea |
| bushy knotweed | Polygonum ramosissimum |
| swamp cottonwood | Populus heterophylla |
| northern pondweed | Potamogeton alpinus |
| threadleaf pondweed | Potamogeton filiformis |
| glaucous rattlesnake-root | Prenanthes racemosa |
| comb-leaved mermaid-weed | Proserpinaca pectinata |
| mock bishop-weed | Ptilimnium capillaceum |
| hairy mountain-mint | Pycnanthemum pilosum |
| creeping spearwort | Ranunculus flammula |
| long-stalked crowfoot | Ranunculus hederaceus |
| prairie coneflower | Ratibida pinnata |
| flame azalea | Rhododendron calendulaceum |
| brown beaked-rush | Rhynchospora fusca |
| beaked-rush | Rhynchospora gracilenta |
| Carolina petunia | Ruellia caroliniensis |
| heart sorrel | Rumex hastatulus |
| slender marsh pink | Sabatia campanulata |
| arrow-head | Sagittaria stagnorum |
| slender bullrush | Scirpus heterochaetus |
| prairie ragwort | Senecio plattensis |
| blue-eyed-grass | Sisyrinchium albidum |
| sand blue-eyed grass | Sisyrinchium arenicola |
| long-stalked greenbrier | Smilax pseudochina |
| small bur-reed | Sparganium minimum |
| Virginia spiraea | Spiraea virginiana |
| ladies'-tresses | Spiranthes magnicamporum |
| slender ladies'-tresses | Spiranthes tuberosa |
| hyssop hedge-nettle | Stachys hyssopifolia |
| buffalo clover | Trifolium reflexum |
| marsh arrowgrass | Triglochin palustre |
| fibrous bladderwort | Utricularia fibrosa |
| northeastern bladderwort | Utricularia resupinata |
| kidney-leaved white violet | Viola renifolia |
| three-parted violet | Viola tripartita |
Appendix 2
Pennsylvania Noxious Weeds
(based on Noxious Weed Control Committee recommendations, 1994).
| COMMON NAME | SCIENTIFIC NAME | DISTRIBUTION IN PA. |
| marijuana | Cannabix sativa | few scattered localities |
| nodding thistle | Carduus nutans | central & SE PA |
| Canada thistle | Cirsium arvense | common throughout state |
| bull thistle | Cirsium vulgare | common throughout state |
| jimsonweed | Datura stramonium | mostly S half of state |
| purple | Lythrum salicaria | wetlands in many parts |
| loosestrife of state | ||
| mile-a-minute | Polygonum | mainly southeastern PA |
| weed | perfoliatum | |
| kudzu | Pueraria lobata | documented from SE PA & Allegheny Co. |
| multiflora rose | Rosa multiflora | throughout state, often planted |
| shattercane | Sorghum bicolor | scattered, mainly easter ssp. drummondii PA |
| Johnsongrass | Sorghum | primarily eastern PA |