| Eschscholzia californica|
It can grow 5–60 cm tall, with alternately branching glaucous blue-green foliage. The leaves are ternately divided into round, lobed segments. The flowers are solitary on long stems, silky-textured, with four petals, each petal 2–6 cm long and broad; their color ranges from yellow to orange, and flowering is from February to September. The petals close at night or in cold, windy weather and open again the following morning, although they may remain closed in cloudy weather.  The fruit is a slender dehiscent capsule 3–9 cm long, which splits in two to release the numerous small black or dark brown seeds. It is perennial in mild parts of its native range, and annual in colder climates; growth is best in full sun and sandy, well-drained, poor soil.
Eschscholzia californica grows hardily in grassy and open areas from sea level to 2,000m (6,500 feet) altitude in the western United States throughout California, extending to Oregon, southern Washington, Nevada, Arizona, New Mexico, and in Mexico in Sonora and northwest Baja California.
It grows well in disturbed areas. In addition to being planted for horticulture, revegetation, and highway beautification, it often colonizes along roadsides and other disturbed areas. It is drought-tolerant, self-seeding, and easy to grow in gardens.
The species is highly variable, and over 90 synonyms exist. Some botanists accept two subspecies, one with four varieties (e.g. Leger and Rice, 2003), though others do not recognise them as distinct (e.g. Jepson 1993):
- E. californica subsp. californica, native to California, Baja California, and Oregon, widely planted as an ornamental, and an invasive elsewhere (see below).
- E.californica subsp. californica var. californica, which is found along the coast from the San Francisco Peninsula north. They are perennial and somewhat prostrate, with yellow flowers.
- E. californica subsp. californica var. maritima (E. L. Greene) Jeps., which is found along the coast from Monterey south to San Miguel Island. They are perennial, long-lived, glaucous, short in stature, and have extremely prostrate growth and yellow flowers.
- E. californica subsp. californica var. crocea (Benth.) Jeps., which grows in non-arid inland regions. They are perennial, taller, and have orange flowers.
- E. California subsp. californica var. peninsularis (E. L. Greene) Munz, which is an annual or facultative annual growing in arid inland environments.
- E. californica subsp. mexicana (E. L. Greene) C. Clark, the Mexican Gold Poppy, which is found in the Sonoran Desert.
- Full sun
- Nutrient-poor, well-drained soils
- Water use is low
- Non-edible with variable toxicity