Canoe a Missouri stream and experience a variety of sounds, smells and sights. Around each watery bend there’s a chance of a calm breeze alive with newly hatched mayflies or migrating monarchs, the melody of a vacationing male prothonotary warbler in the willows or some of the most often encountered riparian sights—cliffs. Whether sandstone, dolomite, limestone, igneous or chert, these jaunting rock faces provide ideal communities for a variety of animals and plants.
Plants living in cliff environments are hardy individuals that carve out a niche of their own within the rocky cracks and crevices. Relying upon the stone-splitting action of seasonal freezing and thawing, roots descend into thin, shallow soils seeking a firm hold. Some, such as tiny ferns and mosses, display mere sprigs of greenery. Others create a splash of vibrant color here and there or simply hang, like dangling jewelry, as in the case of the wild columbine.
Mosses and lichens are adapted to ledges and often appear as carpet-like mats upon undisturbed cliffs. A few herbaceous plants are considered relict species, their geologic roots reaching back to an era when glaciers were a dominant part of the midwestern landscape.
Our state’s landscape is filled with rock-lined rivers such as the Gasconade, White, Meramec, Jacks Fork, Elk, Current and Eleven Point, along with their numerous smaller tributaries. As one navigates these scenic waters with paddle in hand, stone shelters and overhangs may come into view. These dry and moist sites, each with their own mix of stunted woody vegetation, vines, wildflowers and ferns, can be found by most observers.
Not all cliffs are composed the same. Like the variety of fishes found beneath the glistening Ozark waters, so too are the various exposures of Missouri’s rock legends.
Plants differ from one cliff community to the next as well. Often the collection of flora found growing on one type of rock are displayed either sparsely or not at all upon another due to unique microhabitats. While some plants grow upon several different rock face communities, other species are totally restricted to select regional locations within the state. A major determining factor of plant composition on cliffs is the acidity of the soil. Limestone and dolomite cliff soil tends to be basic or not acidic. Sandstone, igneous and chert cliff soil tends to be acidic.
Limestone and Dolomite
With their towering presence measuring 250 feet or more, limestone and dolomite cliffs have become some of our streams’ most recognized structures. Upon these algae-stained, calcium enriched formations grow a dazzling, layered array of lacy ferns, insect-enticing wildflowers, twining vines and stunted, woody plants.
Centuries-old eastern red cedar and Ashe’s juniper are suited to dry limestone and dolomite cliffs and thrive with the sun exposure, while shady ledges damp from spring water seepage provide the perfect climate for maidenhair ferns, alumroot and native hydrangea.
Along the Jacks Fork River in Shannon County, grey limestone cliffs come alive in springtime with the emergence of Tennessee bladder fern fronds and the sounds of courting songbirds.
No fishing, camping or canoeing adventure to this area would be complete without a trip to Jam Up Bluff Natural Area with its unique mix of karst terrain featuring sinkholes, an 80-foot high natural arch and an impressive cavern called Jam Up Cave. If you are lucky, you may even be rewarded on your expedition by the appearance of the rare showy lady’s slipper, an impressive white and pink native orchid that has been documented blooming in Shannon County during May and early June.
Known to many by its aged, meandering nature, the Gasconade River has carved with down-cutting action a well-established scenic river valley and floodplain through the heart of Missouri. Highlighting prominent dolomite formations of the central Missouri Ozarks that are often covered with delicate, light-green fragile ferns, purple cliff brake and bright orange trumpet creeper vines, the Gasconade is a favorite retreat of sightseers, birdwatchers and those wishing to wet a fishing line throughout the year. Gold and bronze-mottled goggle-eye live among the rocks littering the river bottom, created by falling dolomite from high above.
Dolomite cliffs are similar to limestone with a bit more magnesium in their chemical composition. Autumn is a great time to float the Meramec River to view stunning examples. Cloaked in colorful hues of yellow, purple and orange, dwarf hackberries, chinkapin oaks and fragrant sumac often rival spring wildflower displays. Vilander Bluff Natural Area in Crawford County borders the Meramec and showcases classic dolomite and limestone bluffs with eastern red cedars that are more than 300 years old.
Traveling through southern Montgomery County, you can watch turkey vultures floating the thermals atop the unique dolomite formations of Grand Bluffs Conservation Area. Here populations of various glade plants find their niche upon cliffs along the Missouri River.
A snapshot of a typical igneous cliff habitat would show sparsely vegetated granite and rhyolite stone ledges and irregularly jaunting vertical slopes covered with gnarled black jack oaks and lichens. Bluffs of Iron, Shannon, Reynolds and Wayne counties showcase this type of cliff community the best.
Big Creek in southeastern Missouri has, over the centuries, cut its way through Mudlick Mountain, creating giant sheer bluffs and spectacular shut-ins. Here, serviceberry trees, covered with their snow-white blossoms, seem to chant “spring is here” well before other trees break open their tiny buds.
With heights of 100 feet or more, igneous cliffs are exposed to the elements. Storms, prevailing winds, sunlight and extreme temperature fluctuations during both winter and summer take their toll upon any vegetation attempting to live upon the volcanic stone.
Plants that root into the rock strata of the St. Francois Mountains, Johnson’s Shut-Ins and Royal Gorge Natural Area are suited to varying microhabitats. Moist crevices and ledges support liverworts, ferns and algae, while drier sites are composed of glade plants such as tickseed coreopsis, aromatic aster and wild hyacinth.
Visitors touring the Wildcat Glades area of southwest Missouri may view small, restricted chert cliffs. The banks of Shoal Creek showcase dry, sparsely vegetated formations with heights much lower than bluff areas composed of igneous, limestone or dolomite.
During May and June blossoms of columbines grace the moist ledges and vertical cracks. Plants with adaptations more suited to dry, desert-like conditions include eastern prickly pear cactus, armed with its sharp spines and waxy-textured outer covering of succulent stems. Wildcat Glade represents a rare community found only in small-acre patches worldwide.
In contrast to the dry desert nature of the chert at Wildcat, many valleys of the Missouri River in Callaway County are home to moist chert cliffs and rocky terraces composed of lumpy formations known as Graydon Conglomerate. Growing upon more northern and eastern exposures of cliffs within the Earthquake Hollow Conservation Area are populations of ferns and other herbaceous plants that provide a lush habitat for insects, reptiles and amphibians.
Designated a Natural Area in 1986, Pickle Springs entices hikers and campers throughout the year with its dry and moist sandstone formations adorned with short-leaf pine and mountain azalea. Plants found growing in this unique community also include hay-scented ferns and blue ground cedar. Adjacent glades, forests and savannas provide habitat for a variety of plant and animal life, which depend upon sandstone communities for their survival.
Drier sandstone cliff communities commonly display stunted oak and hickories as well as grape vines and sedges. Rocky Hollow Natural Area in Monroe County and Buzzards Bluff in St. Clair County provide good examples of exposed dry sandstone ledges.
Ferns such as mountain spleenwort and common polypody are well adapted to sand-enriched bluffs. Harebell and northern white violet are considered plant relicts and also find refuge upon select moist ledges and cliff overhangs.
Totally restricted to sandstone sites, French’s shooting star flowers for a short time in early to mid-spring. It is a rare treat to come upon this compact and lovely delight with its ruffled, green leaves and pure white flowers. French’s shooting star is listed as a species of conservation concern in Missouri. On a global scale, it is listed as vulnerable.
Current Threats to Cliff Communities
Cliff habitats and their native species are threatened by a host of disturbances. Some of the most damaging are Japanese honeysuckle and kudzu vines and other exotic species, as well as invasion by woody vegetation such as eastern red cedar, which can be aggressive on open cliff habitats.
Domesticated animals can devastate cliff communities, especially those with moist microhabitats. They provide attractive lush vegetation that is prone to overgrazing.
Activities such as rock climbing or rappelling can damage and destroy entire delicate colonies of mosses, ferns and lichens that took many years to become established. Once a microhabitat is disturbed, its composition may change, allowing invaders to get a stronghold and cause even further destruction to the native ecosystem.
When planning your next outdoor adventure, grab a paddle and a pair of binoculars. Then prepare to experience a few of nature’s unique cliff sites firsthand. By observing our natural rock-face communities by canoe or established trails, we can help ensure that our grandchildren and their grandchildren will also be able to experience some cliff hangers of their own along our scenic waterways.