Xanthisma gracile

Xanthisma gracile[1] is a species of annual flowering plant in the aster or sunflower family (Asteraceae) known by the common names slender goldenweed[2] and annual bristleweed.[3]

Xanthisma gracile
Scientific classification
Kingdom:
Plantae
(unranked):
Angiosperms
(unranked):
Eudicots
(unranked):
Asterids
Order:
Asterales
Family:
Asteraceae
Genus:
Xanthisma
Species:
X. gracile
Binomial name
Xanthisma gracile
(Nutt.) D.R.Morgan & R.L.Hartm.
Synonyms
  • Haplopappus gracilis
  • Machaeranthera gracilis

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 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.

Genetics

X. gracile has extra chromosomes that do not have any functional genes (B chromosomes), and about which little is known.[3]

References
  1. Mojave Desert Wildflowers, Pam MacKay, 2nd Ed. p. 314
  2. "Machaeranthera gracilis". Natural Resources Conservation Service PLANTS Database. USDA. Retrieved 26 June 2015.
  3. Mojave Desert Wildflowers, Pam MacKay, 2nd Ed. 2013, p. 218
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