Features appear in each issue of Pennsylvania Heritage showcasing a variety of subjects from various periods and geographic locations in Pennsylvania.

Pennsylvania’s beauty – the gently sweeping valleys, the broad rivers, the rugged mountains and the rolling hillsides – is the bounty which lured waves of settlers to the New World more than three centuries ago. Founder William Penn, entrepreneur and seventeenth century land promoter, heavily advertised his province as “the land good, the air clean and sweet, the springs plentiful, and provisions good and easy to come at … The fields are white for the harvest.” But only recently have Pennsylvanians – and Americans for the matter – rediscovered the great outdoors.

Situated roughly be­tween 40° and 42° north latitude, and 75° and 82° 30′ west longitude, Pennsylvania is in the heart of a great meso­phytic (growing under medium conditions of moisture) forest region. Elevations range from near sea level to an im­mense plateau region whose ridges measure nearly three thousand feet high. The terrain was formed by three signifi­cant river systems: the vast Ohio complex in the western part, the Susquehanna in the east-central and the Dela­ware on the eastern border. Rainfall averages between thirty-five and forty-five inches each year; temperatures vary from -30° F during cold snaps in the northwestern high­lands to sizzling high nineties during the summer in the Philadelphia area. The growing season ranges from about one hundred and thirty to one hundred and seventy frost-free days, stimulating vigorous plant growth.

And Pennsylvania claims some of the most beautiful, as well as wondrous, forests, plants and spectacular wild­flowers.

Pennsylvania’s rich plant life is characterized by a tremendous variety of shapes, structures, sizes and colors. Slime molds actually move and hundreds of mushroom and fungi are unparalleled for their fantastic forms and shapes. Unusual algae, lichens, mosses and liverworts cling to rocks, tree bark and soil. Trees tower so tall that most people do not recognize them as plants as they would the wild chickory which lines high­ways with its distinctive blue flowers. Ferns, horsetails and club-mosses, grasses and sedges cover the earth, too, and are wildflowers in the broad sense.

On Pennsylvania’s moun­tains, along streams and ponds, in marshes and swamps, mingled with crops and, especially, in vast for­ests, wildflowers proliferate. Naturalists have proffered romantic labels for many of the species, including starflower, starwort or golden star, and bellflower, bluebells or oconee­-bells.

Botanists have determined that all plant life has flowers­ – that is, structures made of diverse genetic material which unite to produce offspring. As biologic organizations devel­oped, various parts of the organisms became specialized and distinct. Complicated tissues and mechanisms formed to assure the continuing reproduction of plants. The grandeur of queen slipper blossoms and the exquisite simplicity of panic grass plumes typify the specialization in reproduction. By the close of the Pleistocene epoch (Ice Age), plant forms and wildflowers known today were well estab­lished in North America.

About fifteen thousand years ago, the immense Wis­consin ice sheet covered all of Canada and the United States from Puget Sound southeasterly to the Atlantic Ocean at Long Island. As incredible as it seems, plants sprang up near the borders of the great sheet of ice. Tundra types such as dwarf birth and willow, crowberry, avens, cotton grass and heath cov­ered the Allegheny Plateau and the Appalachian ridges. A narrow band of evergreen spruces, firs and pines bor­dered the tundra. In Penn­sylvania, the lower elevations of the Susquehanna Valley and an area from the Blue Ridge to the Delaware were overgrown by evergreens, deciduous oaks, hickories, maple, ash, basswood, poplars and chestnut.

Toward the end of the Pleistocene epoch, the climate warmed and the ice began to melt. Great changes took place in the exposed soil, but under the ice, the soil had disappeared. In its place was bare rock or varying depths of mixed rock debris cemented together with rock flour formed by the pressure of the terrific weight of ice. Slowly, the pioneering lichens, mosses, horsetails, sedges and ferns became established on the raw ground. Holdfasts and roots stabilized sediments. Exu­dates and decay products broke down rock particles and con­verted rock dust to complex silicates, an essential com­ponent of good soil. As water receded, more ground sup­ported plant life. Insects, herbivores and birds added their discharges and remains, and as temperatures rose, bacteria and fungi grew faster and soil formed quickly. Eventually, an inch or two of real soil appeared and trees and herbaceous plants started to grow. South of the ice front, soils had already been formed and continued to develop even at the height of the great glacier. In the area free from the ice flow, soils be­came deep and productive by the time of colonization.

Floral zones dramatically realigned during the warming period. The tundra and most of what is known as the Northern Evergreen Forest was confined to Canada, but portions of the Mixed Ever­green/Deciduous Forest con­tinued thriving in the west­ern Alleghenies. The Deciduous Forest, which originated in the Gulf area, dominated southern Pennsylvania with oak trees, while beech and maple proliferated in the northern part of the state.

No one area naturally sup­ports every tree and specie that make up the diverse flora of Pennsylvania. Markedly different soils, locations and temperatures enabled about nineteen hundred species of “higher” plants to develop and become established in Pennsylvania. Part of the diver­sity can be attributed, too, to the spread of species from adjacent geographic areas. Northern types, including black spruce, bunchberry, twisted stalk, northern wintergreen and twinflower, found sum­mer temperatures cool enough on the ridges and the Alle­gheny Plateau. Cama lily, spring larkspur, celadine poppy, twin-leaf and cucumber tree grew in the Midwest’s circum­neutral soils. Plants of the southern highlands also took root: white alder, flame azalea, creeping mint, fire-pink and fringed bleeding-heart. A large contingent from the coastal plain such as per­simmon, Maryland golden aster, strawberry bush, swamp hyacinth and blue mist­flower grew in sandy, acidic soil on the Blue Ridge and in the small tract of coastal plain in Bucks County.

The impressive diversity of plants in the Deciduous and Mixed Forest areas is the basis of the stability and strength of ecosystems. About one hundred and twenty-five kinds of trees are pres­ent in these forests, in con­trast with the Northern Ever­green Forest which claims only about eight species. Plant communities with a limited number of types seem to reflect a narrow range of environ­mental conditions. Minor fluctuations in either tem­perature or precipitation, and severe insect or disease at­tack can wipe out any one specie. Marshes, barrens and bogs are especially vulnerable and need protection.

Bogs are interesting for their unusual, if not unique ap­pearance and plant species. As the ice front receded, low areas became acidic and cold water ponds and lakes ap­peared, in which sphagnum moss began to grow. Since or­ganisms do not grow par­ticularly well in these condi­tions, the partially decayed moss built up gradually and eventually filled the depths and covered the water. Herba­ceous plants, shrubs and trees began to thrive when the moss deposits were solid enough, binding the entire mass together with their roots. Black spruce, arborvitae, larch, labrador tea, bog laurel, bog rosemary, calla, bog bean, pitcher plant, sundew, cer­tain bladderworts and north­ern mistletoe are found pre­dominantly in bogs. A typical live bog near Tannersville in the Poconos is now safe-guarded by the Nature Conservancy and may be vis­ited by arrangement.

Bogs evolved into swamps and then moist forests dur­ing a long period. Many former bogs offer local economic value for their rich horticultural peat. When the bogs along U.S. Route 209 in Monroe County were mined for their peat, depths of more than 100 feet were recorded. A few bogs, including one near Mount Bethel, were fed by limey water, spawning a whole different variety of plants such as globe-flower and fringed gentian.

By 1500, the forest had long since reached its climax, in balance with its surroundings and climate. This balance is not static but dynamic, always adjusting in small ways to cyclical changes in weather and from the stress of insect feeding and plant diseases. And by 1500 all possible places for plants to grow were com­pletely occupied; the forest covered the Commonwealth.

Spring flowering woodland plants, now popularly called wildflowers, were widespread and abundant, nurtured by sunlight for about eight weeks before the forest trees leafed out fully. Food for a year was then made and stored to nourish the primordial flower that eventually emerged and carried on reproduction in the succeeding year. Nearly four hundred kinds of spring flower­ing plants adapted to these conditions and filled the forests throughout Pennsylvania.

Plants requiring sun were few and severely limited in range. Monkey-flower, berga­mot, mountain mint, sun­drops, milkweeds, most golden­rods and asters survived only where streams and ani­mal trails or Indian paths cut through the dense forests. Openings in the thick forest cover from storms, floods, fires, and diseases provided light for additional temporary plant homes. But sunny spots seldom last long. Within ten years new cover origi­nates and the canopy reestablishes in about seventy-five years. Sun-loving plants devel­oped effective long range seed dispersal methods to populate newly opened ground that inevitably appeared some­where. Despite their limited habitat areas, almost eight hun­dred sun-loving species even­tually evolved!

Settlers who arrived in response to Penns’s descrip­tions and others’ glowing accounts of the New World labored hard to carve homesteads and cropland out of the still wilderness. Gradually the forest was replaced by farms and towns, followed by cities and canals, roads, railroads and pipelines. Finally, man-made lakes, transmis­sion lines, strip mines, airports, landfills and shopping cen­ters appeared. With every stage of development, new open sites for sun-loving plants occurred and doomed shade lovers lost their ideal habitats.

Approximately twelve hundred species, mostly sun lovers, have been brought to Pennsylvania from other parts of the world since colonization began. Dandelion and queen anne’s lace are as much a part of Pennsyl­vania’s wildflowers now as are trillium and tickseed. Buck­thorns, hawkweeds, chick­weeds, speedwells, ragweeds, mustards and amaranths were unwittingly carried to the Pennsylvania country-side by early settlers in forage for cows and horses. Many arrived mixed in oats and wheat seed stocks, while others spread from sites where ships dumped their ballast before loading cargo.

Forests provided lumber for houses, barns and vehicles; wood for furniture and kitchen utensils; masts for boats; timber for canal Jocks, railroad ties and mine props; chunk­wood for stoves and fire­places; scrap for charcoal and chemicals for the charcoal pits; and essential naval stores from natural pine gum and tree resin. Pigs were ranged in forests to fatten on acorns and chestnuts and whatever else they would eat, includ­ing wildflowers. Sheep and cows stripped the woods bare, too, until farmers learned a century ago that meat grades are better when stock is fed certain provisions from im­proved pastures and high quality feed. The forest, too, provided supplemental income for impoverished families who collected trailing arbutus sods and dogwood blooms for market in spring, and gathered roots, bark and berries for wholesale drug companies.

Because the forests and their treasures were not care­fully husbanded, much besides spring flowers has been lost. But the plant world is renewable. About 18 million of the state’s 29 million acres are now forested. A cut­over forest will eventually return to spring flowers dur­ing a man’s life span, but former plowland and pasture take much longer to rees­tablish. Generally, seeds of spring flowers do not spread rapidly, and once seeds are spread, germination does not occur until a nutrient pool organic layer has accumu­lated. At about the time that this accumulation begins, Japanese honeysuckle, garlic mustard, dame’s rocket and stilt grass become threats to the developing woodland. They effectively block the recovery of woodland plants until their weedy growth is suppressed by a solid forest canopy. Finally, the woodland plants germinate but they might grow for thirty years before they mature enough to flower. The whole sequence from plowland to woodland wildflowers takes 150 years!

Population centers and woodland wildflowers obvi­ously don’t mix. It is hard to imagine the City of Harris­burg in a climax forest, but one could imagine sun-loving plants within the capital city area. Not all of the wildflowers have been lost, nor is it likely that they ever will be. There will always be back roads, hidden valleys and areas far enough from concentrated development to stem the ruina­tion of the forest.

About 3 million acres of state park, forest and gamelands to be untouched. Bar­bara’s buttons will be un­disturbed at Ohiopyle, blazing star at Jennings, the odd rigid arrowleaf at Presque Isle and narrow-leaf gentian at Ricket’s Glen. The one substan­tial stand of jewel shooting star is guarded by Franklin and Marshall College; a large tract of the Pink Hills of Delaware County is main­tained by Tyler Arboretum; and a wide representation of Pennsylvania flora is nurtured at Bowman’s Hill State Wild Flower Preserve in Wash­ington Crossing Historic Park, Bucks County.

Some Pennsylvania wild­flowers never were abundant. Kalm’s lobelia grows only along Bushkill Creek on con­stantly damp seepage, encour­aged by high humidity and cool temperatures. Creeping bluets are found only in Fayette and Somerset counties. Any limited stand of a particular wildflower is vulnerable­ – tassel rue might die out along the Youghiogheny if it does not make enough seed to estab­lish new stands. If Long Pond were drained, closed gen­tian, climbing fem and sheep laurel would disappear. If hemlocks were felled along the Loyalsock, twisted stalk and northern wintergreen would suffer.

Many native plants are hard to locate in the wild. One must climb Chickies Rock over­looking the Susquehanna River to find the remote brad­ley’s spleenwort, or tramp for miles to see the common adders-tongue. To find some plants such as screw stem, a gentian relative, is a real chal­lenge, but field botanists and others find them regularly. As an example of how observational skills may be ex­tended, taxonomists recog­nize eighteen kinds of sunflow­ers in Pennsylvania, whereas an untrained eye might dis­tinguish only five. Only a dozen or so of the one hundred and fifty kinds of water plants have eye-catching display equal to water lilies. The five hundred or more kinds of grasses and sedges play roles -as yet undetermined – in the natural order and they, too, have flowers. At least one hun­dred plants – although many are considered weeds – can be identified in almost every location in Pennsylvania.


For Further Reading

Bailey, Liberty Hyde. The Stan­dard Cyclopedia of Horti­culture. Vol. 2. New York: Mac­Millan & Co., 1935.

Benson, Lyman. Plant Classi­fication. Lexington, Mass.: D.C. Heath and Co., 1959.

Fletcher, Stevenson Whitcomb. Pennsylvania Agriculture and Country Life, 1640-1840. Harrisburg: Pennsylvania Histori­cal and Museum Commission, 1971.

Maffia, Nancy Lee, ed. Ways With Wildflowers. Washington Crossing: Bowman’s Hill Wild­flower Preserve Association, 1983.

Smith, Robert Lee. Ecology and Field Biology. New York: Harper and Row, 1980.

Wherry, Edgar T. and others. Atlas of the Flora of Pennsylvania. Philadelphia: Morris Arboretum of the University of Pennsylvania, 1979.


Oliver J. Stark retired as botanist at Washington Crossing Historic Park in 1984. He served as director of the park’s Bowman’s Hill State Wild Flower Preserve, a one hundred acre sanctuary dedicated to the collection and study of plant life, for eighteen years. A graduate of Cornell University in horticulture, the author has also taught general science. His articles have appeared in Green Scene, Horticulture and American Horticulturist. Prior to his retirement, he received the PHMC’s first annual employee award for outstanding achievement and service to the agency.