Xanthisma spinulosum, Lacy Tansyaster
Scientific Name: Xanthisma spinulosum
Common Name: Lacy Tansyaster
Also Called: Cutleaf Goldenweed, Cutleaf Ironplant, Ironplant, Lacy Tansy-aster, Pinnate Machaeranthera, Spiny Goldenweed, Spiny Haplopappus
Family: Asteraceae, Sunflower Family
Synonyms: (Amellus spinulosus, Aploppus spinulosus, Aster pinnatifidus, Dieteria spinulosa, Diplopappus pinnatifidus, Eriocarpum spp, Haplopappus spp, Machaeranthera autralis, Machaeranthera pinnatifida var. gooddingii, Machaeranthera texensis, Sideranthus australis, Starkea pinnata, more)
Duration: Perennial with a taproot.
Size: Up to 3 feet.
Growth Form: Forb/herb; stems 1 to many, stiff branching throughout; most of the plant bristly hairy.
Leaves: Green; bristly hairy; lower leaves pinnately divided; tipped with white bristly spine; dried at bloom; upper leaves smaller, narrowly linear; margins and teeth tipped with spines.
Flower Color: Yellow; ray flowers bright yellow with 16 or more florets; disk flowers also numerous; flower heads single or small clusters on tips of stiff branches;bracts surrounding flower heads linear, hairy and spiny; fruit is a small achene, pappus whitish tan.
Flowering Season: March to October.
Elevation: 2,000 to 5,000 feet.
Habitat Preferences: Lower and upper desert communities, pinyon-juniper and chaparral habitats, sunny open areas, rocky, sandy and gravelly areas.
Recorded Range: Throughout southwestern and central United States west of the Mississippi River and central Canada. Also recorded in Baja California and northern Mexico. Found throughout Arizona.
North America & US County Distribution Map for Xanthisma spinulosum as Machaeranthera pinnatifida.
U.S. Weed Information: Xanthisma spinulosum is listed in: Weeds of Nebraska and the Great Plains. Plants included here may become weedy or invasive.
Invasive/Noxious Weed Information: No data available.
Wetland Indicator: No data available.
Threatened/Endangered Information: No data available.
Comments: Lacy Tansyasters have variable characteristics and are taxonomically confusing to botanists as evidenced with the many taxonomic changes over the years. Its true classification may yet be resolved. Botanists consider the 5 varieties more as trends rather than absolutes. However, one of its common names "cutleaf" and its scientific epithet "pinnatifid" are clear references to the deeply divided or cut leaves.
Also see in Southwest Desert Flora; Slender Goldenweed, Xanthisma gracilis.