''Penstemon arkansanus'' is a species of flowering plant in the

plantain family Plantaginaceae, the plantain family, is a large, diverse family of flowering plants in the order Lamiales that includes common flowers such as snapdragon and foxglove. It is unrelated to the banana-like fruit also called "plantain." In older cl ...

known by the common name Arkansas beardtongue. It is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

Texas Texas (, ; Spanish language, Spanish: ''Texas'', ''Tejas'') is a state in the South Central United States, South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2 ...

Arkansas Arkansas ( ) is a landlocked state in the South Central United States. It is bordered by Missouri to the north, Tennessee and Mississippi to the east, Louisiana to the south, and Texas and Oklahoma to the west. Its name is from the Osage ...

Oklahoma Oklahoma (; Choctaw language, Choctaw: ; chr, ᎣᎧᎳᎰᎹ, ''Okalahoma'' ) is a U.S. state, state in the South Central United States, South Central region of the United States, bordered by Texas on the south and west, Kansas on the nor ...

Missouri Missouri is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. Ranking List of U.S. states and territories by area, 21st in land area, it is bordered by eight states (tied for the most with Tennessee ...

, and

Illinois Illinois ( ) is a U.S. state, state in the Midwestern United States, Midwestern United States. Its largest metropolitan areas include the Chicago metropolitan area, and the Metro East section, of Greater St. Louis. Other smaller metropolita ...

in the United States, occurring in rocky or sandy soils of

shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especial ...

or sandstone.

Description

''Penstemon arkansanus'' is a perennial herb with clustered stems growing tall. The stems are greyish and

puberulent Trichomes (); ) are fine outgrowths or appendages on plants, algae, lichens, and certain protists. They are of diverse structure and function. Examples are hairs, glandular hairs, scales, and papillae. A covering of any kind of hair on a plant ...

, often turning purplish. The leaves are also finely puberulent, with the longest leaves measuring long. The thyrse makes up just less than half of the plant, with three to nine

fascicle Fascicle or ''fasciculus'' may refer to: Anatomy and histology * Muscle fascicle, a bundle of skeletal muscle fibers * Nerve fascicle, a bundle of axons (nerve fibers) ** Superior longitudinal fasciculus *** Arcuate fasciculus ** Gracile fas ...

s that are each composed of two axillary branches. The

pedicel Pedicle or pedicel may refer to: Human anatomy *Pedicle of vertebral arch, the segment between the transverse process and the vertebral body, and is often used as a radiographic marker and entry point in vertebroplasty and kyphoplasty procedures ...

s are shorter than the main peduncle. The

sepal A sepal () is a part of the flower of angiosperms (flowering plants). Usually green, sepals typically function as protection for the flower in bud, and often as support for the petals when in bloom., p. 106 The term ''sepalum'' was coined b ...

s are long during

anthesis Anthesis is the period during which a flower is fully open and functional. It may also refer to the onset of that period. The onset of anthesis is spectacular in some species. In ''Banksia'' species, for example, anthesis involves the extension ...

and long when the plant is fruiting. The white corolla is long and has purplish veins internally on its

anterior Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

. The tube and narrow throat are long. The glabrous capsule is long and hidden when mature. The plant differs from ''

Penstemon pallidus ''Penstemon pallidus'', the pale beardtongue, is a flower native to the eastern United States. It has been introduced to Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Oce ...

'' only in its tendency to be more glabrous. The plant flowers from late May into early June.

References

{{Taxonbar, from=Q17739549 arkansanus Flora of Arkansas Plants described in 1922