''Xyris tennesseensis'' is a rare species of flowering plant in the family

Xyridaceae The Xyridaceae are a family of flowering plants. This family has been recognized by many taxonomists and is known as the yellow-eyed grass family. The APG II system, of 2003 (unchanged from the APG system of 1998), also recognizes this family, ...

known by the common name Tennessee yellow-eyed grass. It is native to a small section of the

Southeastern United States The Southeastern United States, also known as the American Southeast or simply the Southeast, is a geographical List of regions in the United States, region of the United States located in the eastern portion of the Southern United States and t ...

, including parts of the states of

Alabama Alabama ( ) is a U.S. state, state in the Southeastern United States, Southeastern and Deep South, Deep Southern regions of the United States. It borders Tennessee to the north, Georgia (U.S. state), Georgia to the east, Florida and the Gu ...

Georgia Georgia most commonly refers to: * Georgia (country), a country in the South Caucasus * Georgia (U.S. state), a state in the southeastern United States Georgia may also refer to: People and fictional characters * Georgia (name), a list of pe ...

, and

Tennessee Tennessee (, ), officially the State of Tennessee, is a landlocked U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders Kentucky to the north, Virginia to the northeast, North Carolina t ...

. A federally listed

endangered species An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching, inv ...

, it is threatened by the loss and degradation of its habitat. ''Xyris tennesseensis'' is a perennial herb growing tall. The branching stem is bulbous and fleshy at the base. The leaves are long and narrow and originate at the swollen stem base. They are up to 45 centimeters (18 inches) long and not more than a centimeter (0.4 inch) 45/2.5 wide. They are flat but sometimes twisted, and green with reddish or pink bases.''Xyris tennesseensis''.
''Flora of North America''. Retrieved August 27, 2011. The

inflorescence In botany, an inflorescence is a group or cluster of flowers arranged on a plant's Plant stem, stem that is composed of a main branch or a system of branches. An inflorescence is categorized on the basis of the arrangement of flowers on a mai ...

at the tip of the stem is a cone-like spike covered in tough brown scales. The flowers within are pale yellow. Each spike generally produces one flower per day, or sometimes two.''Xyris tennesseensis''.
''Center for Plant Conservation''. Retrieved August 27, 2011.Kral, Robert. 1978. A new species of ''Xyris'' (sect. ''Xyris'') from Tennessee and northwestern Georgia. Rhodora 80(823): 444–447, f. a–e.
parallel descriptions in English and Latin, commentary in English, line drawings on page 446 The flower opens for a short time in the late morning and closes by mid-afternoon. Blooming occurs in August and September.''Xyris tennesseensis''.
''The Nature Conservancy''. Retrieved August 27, 2011. The plants are

pollinated Pollination is the transfer of pollen from an anther of a plant to the stigma of a plant, later enabling fertilisation and the production of seeds. Pollinating agents can be animals such as insects, for example bees, beetles or butterflies; bird ...

by insects, especially the sweat bee ''

Lasioglossum zephyrus ''Lasioglossum zephyrus'' is a sweat bee of the family Halictidae, found in the U.S. and Canada. It appears in the literature primarily under the misspelling "''zephyrum''". It is considered a primitively eusocial bee (meaning that they do not ha ...

'', which has been observed opening the buds to remove pollen before the flower opens, as to ensure it has first and exclusive access to the pollen. This plant grows in open areas in wet habitat types such as streambanks,

seeps A petroleum seep is a place where natural liquid or gaseous hydrocarbons escape to the Earth's atmosphere and surface, normally under low pressure or flow. Seeps generally occur above either natural terrestrial or underwater petroleum accumul ...

fen A fen is a type of peat-accumulating wetland fed by mineral-rich ground or surface water. It is one of the main types of wetland along with marshes, swamps, and bogs. Bogs and fens, both peat-forming ecosystems, are also known as mires ...

s, and wet meadows. The soils are thin and cover

calcareous Calcareous () is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime (mineral), lime or being chalky. The term is used in a wide variety of Science, scientific disciplines. In zoology ''Calcare ...

rock. The plant grows in neutral to basic soils, unlike other ''

Xyris ''Xyris'' is a genus of flowering plants, the yelloweyed grasses, in the yellow-eyed-grass family. The genus counts over 250 species, widespread over much of the world, with the center of distribution in the Guianas. The leaves are mostly dis ...

'' species, which usually occur in acidic soils. There are 16 to 25 populations of the plant in three US states. Some have been recently

extirpated Local extinction, also extirpation, is the termination of a species (or other taxon) in a chosen geographic area of study, though it still exists elsewhere. Local extinctions are contrasted with global extinctions. Local extinctions mark a chan ...

, others are declining, and several others are in danger of destruction. Threats to the species include

habitat destruction Habitat destruction (also termed habitat loss or habitat reduction) occurs when a natural habitat is no longer able to support its native species. The organisms once living there have either moved elsewhere, or are dead, leading to a decrease ...

during

timber Lumber is wood that has been processed into uniform and useful sizes (dimensional lumber), including beams and planks or boards. Lumber is mainly used for construction framing, as well as finishing (floors, wall panels, window frames). ...

operations, including

clearcutting Clearcutting, clearfelling or clearcut logging is a forestry/logging practice in which most or all trees in an area are uniformly cut down. Along with Shelterwood cutting, shelterwood and Seed tree, seed tree harvests, it is used by foresters t ...

. Timber companies own much of the land occupied by the plant in Tennessee. Removal of stands of trees causes the soil to dry, making it inhospitable for this wetland endemic plant. Road construction and maintenance, including

herbicide Herbicides (, ), also commonly known as weed killers, are substances used to control undesired plants, also known as weeds.EPA. February 201Pesticides Industry. Sales and Usage 2006 and 2007: Market Estimates. Summary in press releasMain page f ...

application, is a threat. The plant requires open, sunny habitat for

germination Germination is the process by which an organism grows from a seed or spore. The term is applied to the sprouting of a seedling from a seed of an angiosperm or gymnosperm, the growth of a sporeling from a spore, such as the spores of fungi, ...

and growth, and it is threatened by the encroachment of large and woody vegetation in some areas. Proper

land management Land management is the process of managing the land use, use and development of land resources. Those resources are used for a variety of purposes for example agriculture, forestry, water resource management, Human settlement, human settlements an ...

includes the clearing of brush and the removal of exotic plant species such as Nepal grass (''Microstegium vimineum'').

Interactions with other species

Flowers of ''Xyris tennesseensis'' are visited by the primitively social sweat bee, '' Lasioglossum zephyrum''. This bee is known to force open the plant's flowers, granting the bee priority access to the pollen.

References

{{Authority control tennesseensis Plants described in 1978 Flora of the Southeastern United States