Donate Sign up for e-network
CENTER for BIOLOGICAL DIVERSITY Because life is good

Content on this page requires a newer version of Adobe Flash Player.

Get Adobe Flash player

Plants are a kingdom of life forms that includes familiar organisms such as trees, herbs, bushes, grasses, vines, ferns and mosses. Through photosynthesis, they convert water and carbon dioxide into the oxygen we breathe and the sugars that provide the primary fuel for life. Through nitrogen fixation, plants generate proteins that are basic building blocks of life. Early fossil records of photosynthesizing organisms date from about 3 billion years ago. Plants were instrumental to evolution as a whole in that they produced the oxygen that made life on Earth possible — not only by "breathing" it into the atmosphere and transforming it, but also by crushing rocks with their roots, which created soils and released nutrients on a large scale. Plants are crucial to the existence of all other living creatures on Earth, both through the systemic life-support services they sustain and the food, medicine and other material resources they provide. The total number of described plant species hovers around 250,000.

Our information on plant species numbers is far from perfect. The International Union for the Conservation of Nature’s Red List estimates that about 54 percent of evaluated plant species (not nearly all the plants on Earth) are threatened: 10,584 out of 19,738. Other estimates say about one in eight plants is considered at risk of extinction globally, putting the U.S. number at one-third. The Red List says 279 evaluated plants are threatened in the United States.

Ash Meadows gumplant
Aboriginal prickly apple cactus
Canelo Hills ladies' tresses
Cape Sable thoroughwort
Carter's small-flowered flax
Coachella Valley milk vetch
Coleman's coralroot
Cook's lomatium
Florida brickell-bush
Florida semaphore cactus
Holmgren's milk vetch
Huachuca water umbel
Johnson's seagrass
Lane Mountain milk vetch
Large-flowered woolly meadowfoam
Las Vegas buckwheat
Munz's onion
North Carolina golden sedge
Pallid manzanita
Peirson's milk vetch
Pima pineapple cactus
Sacramento Mountains thistle
San Bernardino bluegrass
San Diego ambrosia
San Jacinto Valley crownscale
Shivwitz milk vetch
Spreading navarretia
Thread-leaved brodiaea
Virgin Islands plants
Willowy monardella

:Photo © Lorena B. Moore