''Amsonia tharpii'' is a species of flowering plant in the family

Apocynaceae Apocynaceae (, from '' Apocynum'', Greek for "dog-away") is a family of flowering plants that includes trees, shrubs, herbs, stem succulents, and vines, commonly known as the dogbane family, because some taxa were used as dog poison. Notable mem ...

, known by the common names Tharp's bluestar and feltleaf bluestar. It is native to

New Mexico New Mexico is a state in the Southwestern United States, Southwestern region of the United States. It is one of the Mountain States of the southern Rocky Mountains, sharing the Four Corners region with Utah, Colorado, and Arizona. It also ...

and

Texas Texas ( , ; or ) is the most populous U.S. state, state in the South Central United States, South Central region of the United States. It borders Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the we ...

in the United States.''Amsonia tharpii''.
Center for Plant Conservation. This plant is a perennial herb with a woody

taproot A taproot is a large, central, and dominant root from which other roots sprout laterally. Typically a taproot is somewhat straight and very thick, is tapering in shape, and grows directly downward. In some plants, such as the carrot, the taproot ...

. It grows up to about 20 centimeters tall. The linear to lance-shaped leaves are each up to 3 centimeters long and are whorled about the stem. The leaves lower on the plant are wider than those near the top.''Amsonia tharpii''.
New Mexico Rare Plants. The white, pale blue,''Amsonia tharpii''.
The Nature Conservancy. or greenish flowers are borne in clusters at the stem tips. They are tubular and about 1.5 centimeters long. The fruit is a two-lobed follicle. The cylindrical seeds are about a centimeter long. There are three populations of this plant in New Mexico in Eddy County, and there is a single population in Texas, in

Pecos County Pecos County ( ) is a county located in the U.S. state of Texas. As of the 2020 census, its population was 15,193. The county seat is Fort Stockton. The county was created in 1871 and organized in 1875.. By Glenn Justice and John Leffler. Re ...

. The New Mexico and Texas sites are over 160 kilometers apart. The plant is probably a relict species, rare now that conditions have changed since it was more abundant. Today it grows on

limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...

and

gypsum Gypsum is a soft sulfate mineral composed of calcium sulfate Hydrate, dihydrate, with the chemical formula . It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, drywall and blackboard or sidewalk ...

substrates in Chihuahuan Desert scrub vegetation. The plant is threatened by the loss and degradation of its habitat. In New Mexico it is threatened by oil and gas development and the changes that have occurred on the land due to

overgrazing Overgrazing occurs when plants are exposed to intensive grazing for extended periods of time, or without sufficient recovery periods. It can be caused by either livestock in poorly managed agricultural applications, game reserves, or nature ...

, such as

erosion Erosion is the action of surface processes (such as Surface runoff, water flow or wind) that removes soil, Rock (geology), rock, or dissolved material from one location on the Earth's crust#Crust, Earth's crust and then sediment transport, tran ...

and

introduced species An introduced species, alien species, exotic species, adventive species, immigrant species, foreign species, non-indigenous species, or non-native species is a species living outside its native distributional range, but which has arrived ther ...

of plants. In Texas, the plant grows on roadsides and it may be threatened by roadway maintenance.

References

External links

USDA Plants Profile
{{Taxonbar, from=Q4748805 tharpii Flora of New Mexico Flora of Texas