White Tackstem
Calycoseris wrightii
Observed in Telegraph Pass at South Mountain, Phoenix, Maricopa Co., Arizona. April 2010.
FLOWERS: All of the florets in the head are strap shaped with those
around the perimeter enlarged as rays; the ends of most straps have five teeth.
The peduncle below the flower head is beset with many gland-tipped hairs that
appear as tacks. Blooming mostly March and April.
ANNUAL: A spring annual plant with several erect stems reaching sometimes
0.5 meter often growing up and through low shrubs. Absent in
dry years. Stem breaks exude milky sap.
LEAVES: Leaves are pinnately divided with long, linear lobes. Leaves at
soil level are largest, those above much smaller.
RANGE: In Sonoran Desert at middle and lower elevations but spotty in
distribution; absent in some spots and abundant in others. Found from Texas to
California.
FRUIT: Mature seeds have a series of slender bristles at the top.
UNARMED