The common sun rose is a species of plant endemic to California. It bears the scientific name of Crocanthemum scoparium, but is sometimes included in the genus Helianthemum. Its common names include peak rockrose, Bisbee peak rushrose, broom-rose and peak rushrose. There are two recognized varieties, both uncommon.
It is found in dry, sandy areas in hills and low mountains, primarily along the coast from the Bay Area southward, with a concentration in San Diego County. It is also present in the San Bernardino Mountains and San Gabriel Mountains within San Bernardino County.
Crocanthemum scoparium is a small perennial shrub bearing long, smooth stems and small flowers each with five bright yellow petals. It falls within the cistaceae (rockrose) family.
Under normal conditions these plants are about a foot-and-a-half tall and roughly a foot-and-a-half wide. They are semi-deciduous, meaning they lose their foliage for a very short period, when old leaves fall off and new foliage growth is starting. In the case of the crocanthemum scoparium, this occurs in the summer, when the bright green foliage withers and drops off.
A perennial, this shrub sports hairs generally in stellate clusters and is rarely glandular, except in its inflorescence. The growth can vary from very sparse to dense, dependent upon the degree of irrigation and its extent of exposure to the sun and withering or drying conditions.
The stems of the plant are generally erect, and more or less broom-like. The leaves are cauline and generally alternate and linear to lanceolate or oblanceolate.
The inflorescence is a raceme or is panicle-like, meaning the oldest flowers are borne towards the base and new flowers are produced as the shoot grows, with no predetermined growth limit. The flowers consist of five sepals, with the outer two generally narrower; and the petals yellow. The fruit is generally three-valved. Each flower will produce at least three seeds and sometimes many more.
Its name helianthemum is from the Greek for sun flower.
This species will persist and be especially abundant after fire scorches the earth near where it has gown in the past.
One insect known to feed off of it is the common gray moth, know scientifically as the Anavitrinella pampinaria.

From Wikipedia and https://calscape.org.