Machaeranthera gracilis
Encyclopedia
Machaeranthera gracilis (syn.
Xanthisma gracile) is a species of flowering plant in the aster family
known by the common names slender goldenweed and annual bristleweed. It is native the southwestern United States and northern Mexico, where it grows in the deserts and plateaus. It is a bristly annual herb growing erect up to 45 centimeters tall. The oval or oblong are 1 to 3 centimeters long and divided into lobes or teeth tipped with bristles. The inflorescence
bears one or more flower heads
lined with pointed, roughly hairy phyllaries
. 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
2 to 3 millimeters long tipped with a pappus
.
Synonym (taxonomy)
In scientific nomenclature, a synonym is a scientific name that is or was used for a taxon of organisms that also goes by a different scientific name. For example, Linnaeus was the first to give a scientific name to the Norway spruce, which he called Pinus abies...
Xanthisma gracile) is a species of flowering plant in the aster family
Asteraceae
The Asteraceae or Compositae , is an exceedingly large and widespread family of vascular plants. The group has more than 22,750 currently accepted species, spread across 1620 genera and 12 subfamilies...
known by the common names slender goldenweed and annual bristleweed. It is native the southwestern United States and northern Mexico, where it grows in the deserts and plateaus. It is a bristly annual herb growing erect up to 45 centimeters tall. The oval or oblong are 1 to 3 centimeters long and divided into lobes or teeth tipped with bristles. The inflorescence
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. Strictly, it is the part of the shoot of seed plants where flowers are formed and which is accordingly modified...
bears one or more flower heads
Head (botany)
The capitulum is considered the most derived form of inflorescence. Flower heads found outside Asteraceae show lesser degrees of specialization....
lined with pointed, roughly hairy phyllaries
Bract
In botany, a bract is a modified or specialized leaf, especially one associated with a reproductive structure such as a flower, inflorescence axis, or cone scale. Bracts are often different from foliage leaves. They may be smaller, larger, or of a different color, shape, or texture...
. 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
Achene
An achene is a type of simple dry fruit produced by many species of flowering plants. Achenes are monocarpellate and indehiscent...
2 to 3 millimeters long tipped with a pappus
Pappus (flower structure)
The pappus is the modified calyx, the part of an individual disk, ray or ligule floret surrounding the base of the corolla, in flower heads of the plant family Asteraceae. The pappus may be composed of bristles , awns, scales, or may be absent. In some species, the pappus is too small to see...
.