''Ambrosia linearis'' is a species of flowering plant in the family

Asteraceae The family Asteraceae, alternatively Compositae, consists of over 32,000 known species of flowering plants in over 1,900 genera within the order Asterales. Commonly referred to as the aster, daisy, composite, or sunflower family, Compositae w ...

known by the common names streaked bur ragweed, Colorado bursage, linear-leaf bursage, and plains ragweed. 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 ...

to east-central part of the state of

Colorado Colorado (, other variants) is a state in the Mountain West subregion of the Western United States. It encompasses most of the Southern Rocky Mountains, as well as the northeastern portion of the Colorado Plateau and the western edge of t ...

in the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

, where it occurs in Elbert, Pueblo,

El Paso El Paso (; "the pass") is a city in and the seat of El Paso County in the western corner of the U.S. state of Texas. The 2020 population of the city from the U.S. Census Bureau was 678,815, making it the 23rd-largest city in the U.S., the s ...

Cheyenne The Cheyenne ( ) are an Indigenous people of the Great Plains. Their Cheyenne language belongs to the Algonquian language family. Today, the Cheyenne people are split into two federally recognized nations: the Southern Cheyenne, who are enroll ...

, Crowley,

Kiowa Kiowa () people are a Native American tribe and an indigenous people of the Great Plains of the United States. They migrated southward from western Montana into the Rocky Mountains in Colorado in the 17th and 18th centuries,Pritzker 326 and eve ...

and Lincoln Counties.''Ambrosia linearis''.
The Nature Conservancy.Biota of North America Program 2014 county distribution map
/ref> This species is a perennial herb or

subshrub A subshrub (Latin ''suffrutex'') or dwarf shrub is a short shrub, and is a woody plant. Prostrate shrub is a related term. "Subshrub" is often used interchangeably with "bush".Jackson, Benjamin, Daydon; A Glossary of Botanic Terms with their Der ...

growing up to 40 centimeters or more in height. The leaves are mostly linear. Some are divided into lobes which are linear. They vary in length, measuring up to a few centimeters long. Like some other ''Ambrosia'', the male and female

flower heads A pseudanthium (Greek for "false flower"; ) is an inflorescence that resembles a flower. The word is sometimes used for other structures that are neither a true flower nor a true inflorescence. Examples of pseudanthia include flower heads, compos ...

are clustered separately on the

inflorescence An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Morphologically, it is the modified part of the shoot of seed plants where flowers are formed o ...

. The female head has a single floret while the male head contains several. The fruits are contained within a spiny

bur A bur (also spelled burr) is a seed or dry fruit or infructescence that has hooks or teeth. The main function of the bur is to spread the seeds of the bur plant, often through epizoochory. The hooks of the bur are used to catch on to for exam ...

.''Ambrosia linearis''.
Flora of North America. The plant can reproduce

vegetatively Vegetative reproduction (also known as vegetative propagation, vegetative multiplication or cloning) is any form of asexual reproduction occurring in plants in which a new plant grows from a fragment or cutting of the parent plant or spec ...

as well as sexually. There are many populations of this plant, but several are basically "roadside occurrences that occupy ditches."''Ambrosia linearis''.
Center for Plant Conservation. It commonly occurs along roadsides; in fact, "most of the eastern half of El Paso County is one vast roadside occurrence of this species". Otherwise, the plant grows in

playa lakes A dry lake bed, also known as a playa, is a basin or depression that formerly contained a standing surface water body, which disappears when evaporation processes exceeds recharge. If the floor of a dry lake is covered by deposits of alkaline c ...

and other seasonally wet habitat types. This bursage is adapted to the disturbance created by the seasonal cycle in this part of the

shortgrass prairie The shortgrass prairie is an ecosystem located in the Great Plains of North America. The two most dominant grasses in the shortgrass prairie are blue grama (''Bouteloua gracilis'') and buffalograss (''Bouteloua dactyloides''), the two less domina ...

vegetation. Fewer populations occur in this good quality habitat than on roadsides and in ditches. This species is threatened by the development of land for housing and agriculture, which consumes terrain with playa lakes and other appropriate native habitat.

References

{{Taxonbar, from=Q4741894 linearis Flora of Colorado Plants described in 1905