Emory's rock daisy

Perityle emoryi, Emory's rock daisy, is a highly variable annual herb in the Asteraceae ranging from 2 to 60 centimeters tall, with stems varying from delicate and unbranched to thick, sprawling and many-branched. The plant is hairy and glandular throughout, with alternately arranged leaves that are toothed to deeply lobed. Inflorescences are hemispheric to bell-shaped composite heads less than one centimeter wide, each bearing numerous golden disc florets surrounded by 8 to 12 white ray florets; the fruit is a small flattened achene. A polyploid species displaying considerable genetic and morphological variability, it exhibits an amphitropical distribution between the deserts of southwestern North America (Arizona, California, Nevada, Utah and northern Mexico from Sonora to Sinaloa) and western South America, also occurring on Guadalupe Island and introduced in Hawaii. It is a characteristic plant of desert washes, rocky slopes and disturbed ground and tolerates disturbance well, sometimes becoming weedy.