What are Plants?
Producing their food through photosynthesis, plants include all photosynthetic organisms found within the taxonomic kingdom Plantae. Kingdom Plantae is further organized into taxonomic divisions. The majority of divisions include nonvascular plants such as algae, liverworts, hornworts, mosses, and flagellates. Nonvascular plants lack a vascular system that conducts water in vascular tissues throughout the plant. Vascular plants, members of the subkingdom Tracheobionta, do have vascular tissues. Vascular plants include ferns, club mosses, angiosperms (flowering plants) and gymnosperms (non-flowering plants).

Southeastern Species of Greatest Conservation Need Learn more about regional plants species of greatest conservation need by browsing our species information Web application.

Photosynthetic organisms within the taxonomic kingdom Plantae common to the southeastern U.S. are presented below.

	Club Mosses (division Lycopodiophyta) Vascular club mosses are generally larger than nonvascular mosses and bear resemblance to some ferns.
	Ferns and Fern Allies (division Pteridophyta) Ferns are non-flowering plants characterized by leaf-like structures called fronds and true roots originating from a rhizome. Fern allies are not ferns but are similar to ferns because they reproduce with spores.
	Gymnosperms (division Coniferophyta) Gymnosperms are non-flowering plants including conifers, which are cone-bearing trees such as pine, spruce, and fir trees.
	Angiosperms (division Magnoliophyta) Angiosperms are flowering, seed bearing plants that form seeds in fruits. This includes flowering trees, shrubs, forbs, and grasses.

	Algae and single-celled photosynthetic organisms Algae and photosynthetic microorganisms such as phytoplankton are important components of many aquatic ecosystems with both positive and negative impacts. Microflora are important food sources, but Algae Bloom and Red Tides can be harmful and toxic.
	Lichens and Fungi Although not truly a plant, lichens are plant-like colonies of mutualistic fungi and algae existing in a symbiotic relationship.
	Liverworts and Hornworts (division Hepatophyta) Liverworts are primitive photosynthetic plants with no vascular system.
	Mosses and Hornworts (division Bryophyta) These plants have no roots, leaves, or stems. They must live near water or other moist locations.

Ecological Importance of Plants
Plants are a cornerstone of the foundations of life in ecosystems. Thought of as producers, plants capture light energy radiated from the sun and convert it into the sugars and starches that other organisms consume for energy. In addition to producing energy, plants convert raw materials present in the ecosystem such as carbon from the atmosphere and inorganic minerals and compounds from the soil including nitrogen, potassium, and iron and make these elemental nutrients available to other life forms. From the simplest plants, such as algae, to towering forest trees such as Oaks, plants provide food and habitat. Plant communities provide shelter, cycle nutrients, and protect water quality.

Plants of the Southeastern United States
Flora size in North America is greatest in the southeastern United States. The high diversity may be related to the region's warm, humid climate, which is thought to be favorable for plant growth (Sisk, 1998).

The U.S. Department of Agriculture PLANTS database lists 20,619 plant species found in the Southeastern U.S. region encompassing Kentucky, Tennessee, North Carolina, South Carolina, Georgia, Alabama, and Mississippi [view data records]. Of these, 1,027 species are recognized by state or federal agencies as threatened or endangered species [view data records].

State-listed Noxious Weeds
As of 2008, The USDA PLANTS database identifies nine state-listed noxious weed species in Kentucky [view records], three species in Tennessee [view records], 152 species in North Carolina [view records], 136 species in South Carolina [view records], 132 species in Alabama [view records], and nine species in Mississippi [view records]. A state noxious weed list for Georgia is not currently available.

Wetland Indicator Plant Species
The USDA PLANTS database lists 2550 plant species that are wetland indicators in Kentucky, Tennessee, North Carolina, South Carolina, Georgia, Alabama, and Mississippi [view records].

For more about plants, see the Web resources for plants of the southeastern United States on this page.