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Although published in 1993, the new atlas is already out-of-date.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