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Here we provide some basic information on plants and plant communities found in and near the Cahaba River.  We offer three categories of information.  With time more information will be provided.

Aquatic Plants
Riparian Plants
Unique Terrestrial Plant Communities of the Watershed

 

 

The Cahaba Riverand its watershed may have a wide variety of animal species, but it is also home to many plant species, some of which are considered rare, threatened, or endangered.  Indeed, much of rich biodiversity we have in Alabama is a result of the rich array of plant communities found throughout the state. Alabama can be divided into five distinct geologic (or physiographic) regions, and each has unique sub-regions (or provinces) that provide different environments for the plants and animals there.  This helps create a tremendous amount of species diversity in the state.  The Cahaba River originates in the Valley and Ridge physiographic region, and then travels through the East Gulf Coastal Plain until it joins the Alabama River.  The place where the Cahaba enters the Coastal Plain is known as the Fall Line.  

 

Through their ability to harness energy from the sun and convert it into sugar, plants provide all of the energy that supports the animals living in rivers and streams.  Some of this energy comes from leaves, branches and logs that fall into the river from the forests surrounding the river. As this material decays (via the action of bacteria and fungi), it is eaten and processed by small aquatic animals, especially insects. In addition, some of the energy that supports the aquatic food web comes from plants living in the river.  These are aquatic plants, some of which are featured below.

 

  Plants in the Riverare those plants that live in the water. They come in many shapes and sizes.  Some of the most important ones are the smallest and most inconspicuous.  Others, like the shoals lily, are large, flashy, and much appreciated by the public.
  Cahaba Lily:  Better known as the shoals lily, these lilies occur along a limited stretch of the Cahaba River, mainly in Bibb County, Alabama.  Sand and gravel collects in rocky outcrops in shallow stretches of the river and the lilies establish themselves in these sediments. Thus, the lilies generally occur on shallow portions of the river (or 'shoals') and not in adjacent deeper water. The Cahaba River Society sponsors several canoe trips to see the lilies and there is an annual Cahaba Lilly Festival in West Blockton, Bibb County. 
  AlgaeAlgae are a very important source of energy for aquatic food webs.  Three very different types of organisms are included in this category: cyanobacteria, diatoms, and green algae. Each of these three types of plants contribute to the slippery film that often covers rock and other surfaces in streams. Called 'biofilm' this biologically diverse layer provides food to snails, some fish, and other creatures of the stream community.   When drifting in the current as microscopic cells or strings of cells, these plants are called 'phytoplankton'. Phytoplankton are an important source of food to filter-feeding animals like clams, mussels, some fish and some invertebrates.

 

  Cyanobacteria (pictured at right) are microscopic plants that are abundant in streams and rivers.  They provide a small, but much-needed source of nitrogen to aquatic food webs. Cyanobacteria were once called 'blue-green algae'.
 

Diatoms (pictured at right) are microscopic plants that can be part of the biofilm on submerged structures or can be free-floating.  Diatoms are often the most important source of plant energy that is generated within the stream (as opposed to plant material that originates on land near the stream).  Diatoms can attached to a substrate, or can float along in the current.

 

  Green algae (pictured at right) as individual cells are microscopic. But these plants often grow into long filaments that are readily noticeable in streams as long plumes of green material (often incorrectly called 'moss' by visitors to the stream) Green algae also contributes to the biofilm, but smaller filaments can float in the current.

 

  Riparian Plants

'Riparian' refers to the land immediately adjacent to a river or stream.  Riparian forests, for example, are those forests near the river and are greatly influenced by the river's actions (e.g., flooding).  Such forests often have plant species who prefer habitats that are cool and moist. 

 

 

Mountain Laurel The mountain laurel (Kalmia latifolia) is a beautiful flowering shrub often found on the cliffs and steep slopes overhanging the upper Cahaba river. The mountain laurel prefers well-drained, acidic soils and is distributed from Maine to the Gulf Coast. It is sometimes planted in gardens, but grows best in the wild. Characteristic of the mountain laurel are glossy evergreen leaves and clusters of light pink flowers appearing in late spring.

 

Painting by Mary Vaux Walcott

  Riparian Trees:  Many tree species can be found in the Cahaba's riparian forests.  The following trees are some of the common in these forests.  Some are only rarely found away from streams or rivers in the upper Cahaba watershed.  This list is not meant to be exhaustive, but should be helpful for teachers who want to feature tree species often associated with the river's riparian forest.

River Birch (Betula nigra)
Swamp Dogwood (Cornus stricta)
Water Oak (Quercus nigra)
Willow Oak (Quercus phellos)
Winged Elm (Ulmus alata)
American Elm (Ulmus americana)
Yellow-poplar, Tulip-poplar (Liriodendron tulipifer)
Sweetgum (Liquidamber styraciflua)
Sycamore (Plantanus occidentalis)
Red Maple (Acer barbatum)
Horse-sugar, Sweetleaf (Symplocos tinctoria)
Buttonbush (Cephalanthus occidentalis)
Persimmon (Diospyros virginiana)
Diamond Leaf Oak (Quercus laurifolia)
American Hornbeam, Ironwood, Musclewood (Carpinus caroliniana)
Eastern Hophornbeam (Ostrya virginiana)
Bitternut Hickory (Carya cordiformis)
Black Willow (Salix nigra)

 
  Tree Identification Websites Several websites offer excellent descriptions and pictures of trees found in Alabama.  

Trees of Alabama and the Southeast
 

100 Trees of Alabama
 

Wetland Plant Identification
 

 

 

 
  Unique Terrestrial Communities of the Watershed
  Mountain Longleaf Pine

One very important plant community is that of the Mountain Longleaf Pine.  These forests are some of the most biodiverse forests in North America, containing numerous endangered and threatened plant and animal species. Longleaf Pine forests, once covering nearly 100 million acres in the southeastern US, but are now found on less than 2 million acres. These forests are increasingly a focus of conservation efforts.

The zone of longleaf forests found in the hilly and mountainous regions of north central Alabama are called Mountain Longleaf Pine Forests.  These forests differ from the much more widespread longleaf forests on the flat-to-rolling terrain of the coastal plain. The mountainous variety of these forests harbor their own unique combination of plant and animal species not found elsewhere.  Where these forests are on mountain ridges, you can find exposed bedrock and boulders in the understory, and the view of the forest and surrounding lowlands is often spectacular! One place to view Mountain Longleaf Pine Forests is at Oak Mountain State Park in Shelby County, though pockets of remnant forest can be found throughout the region.

The longleaf pine forests disappeared due to unsustainable logging, fire suppression, conversion of forest into agriculture, and, more recently, urban/suburban sprawl. Because Longleaf Pine trees only regenerate in sunny habitats, the trees and associated plant and animal species rely on low-intensity fires to keep the forest open and keep fire-intolerant forest species from invading. Historically, natural, lightning generated fires provided this service, but increasingly, prescribed (or 'controlled') fires are needed to keep these ecosystems intact.

 

 

Dolomite Glades

Dolomite is a sedimentary rock composed chiefly of the carbonates of calcium and magnesium. At least half of the rare plant species of Bibb County are found primarily on or near open, mostly treeless glades that have developed over this Dolomite rock formation. 

Bibb County, located in the Cahaba River watershed, contains a considerable number of rare plant species. Eight brand new species, previously unknown to science were discovered in 1992 in Bibb County. These eight species are endemic to these few small glades on the banks of the Lower Little Cahaba River.  This means that this is the only known location where these plants can be found. Following this huge discovery, Bibb County has been recognized as having the most diversity of rare plant species of any county in the temperate Southeast. Bibb County is also home to the many populations of plants that are either listed under the Endangered Species Act or that are candidates for listing.  In addition to these, this county is also known to have nearly 25 other species on the Alabama Natural Heritage Programís Rare Plant List. Below are some examples.  Click on the species below to see photographs of these beautiful new discoveries.

 

 

Endemic Plants of the Bibb County Dolomite Glades

Alabama gentian-pinkroot  (Spigelia gentianoides var. alabamensis )

Cahaba daisy fleabane  (Erigeron strigosus var. dolomiticola)

Cahaba paintbrush  (Castilleja kraliana)

Cahaba prairie-clover  (Dalea cahaba)

Cahaba torch  (Liatris oligocephala)

Deceptive marbleseed  (Onosmodium decipiens)

Ketona tickseed   (Coreopsis grandiflora var. inclinata)

Sticky rosinweed   (Silphium glutinosum)

 

  Sources:

Glades plant photographs:  Jim Allison - http://www.mindspring.com/~jallison/
Other sources of information: Jaynes, Richard A. Mountain Laurel Horticulture v. 98 no. 2 (March 2001) p. 32-34
See References for other sources