''Xanthisma gracile'' is a species of annual flowering plant in the family

Asteraceae Asteraceae () is a large family (biology), family of flowering plants that consists of over 32,000 known species in over 1,900 genera within the Order (biology), order Asterales. The number of species in Asteraceae is rivaled only by the Orchi ...

known by the common names slender goldenweed and annual bristleweed.Mojave Desert Wildflowers, Pam MacKay, 2nd Ed. 2013, p. 218

Range and habitat

It is native the southwestern United States and northern Mexico, where it grows in the deserts and plateaus.

Growth pattern

It is a bristly annual herb growing erect up to 45 cm tall.

Leaves and stems

The oval or oblong leaves are 1–3 cm long and divided into lobes or teeth tipped with bristles.

Flowers and fruit

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 ...

bears one or more

flower heads A pseudanthium (; : pseudanthia) 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, composite flowers ...

lined with pointed, roughly hairy

phyllaries In botanical terminology, a phyllary, also known an involucral bract or tegule, is a single bract of the involucre of a composite flower. The involucre is the grouping of bracts together. Phyllaries are reduced leaf-like structures that form one o ...

. The head has a center of many yellow disc florets and a fringe of 16 to 18 yellow ray florets roughly a centimeter long. The fruit is a woolly

achene An achene (; ), also sometimes called akene and occasionally achenium or achenocarp, is a type of simple fruit, simple dry fruits, dry fruit produced by many species of flowering plants. Achenes are monocarpellate (formed from one carpel) and Dehi ...

2 to 3 millimeters long tipped with a pappus.

Genetics

''Xanthisma gracile'' has extra chromosomes that do not have any functional genes (

B chromosomes In addition to the normal karyotype, wild populations of many animal, plant, and fungi species contain B chromosomes (also known as supernumerary, accessory, (conditionally-)dispensable, or lineage-specific chromosomes). By definition, these chr ...

), and about which little is known.

References

External links

Jepson Manual TreatmentUSDA Plants ProfileFlora of North AmericaUC Photos gallery
Astereae Flora of Mexico Flora of the Western United States Flora of the California desert regions Taxa named by Thomas Nuttall Plants described in 1848 {{Astereae-stub