California poppy is a perennial or annual plant growing to 5–12 in (13–30 cm) tall[2] with alternately branching glaucous blue-green foliage.

[4] The fruit is a slender, dehiscent capsule 3 to 9 cm (1.2 to 3.5 in) long, which splits in two, sometimes explosively with an audible snap, to release numerous small 1.5–1.8 mm (0.059–0.071 in) wide black or dark brown seeds.

Some botanists accept two subspecies—one with four varieties (e.g., Leger & Rice 2003)—though others do not recognize them as distinct (e.g., Jepson 1993): Botanical research has held significant implications towards the classification of Eschscholzia.

A UK study of meadow flowers including commercial mixes and common plants such as ragwort and dandelion ranked the California poppy highly in pollen production, although it did not produce a significant amount of nectar.

When measuring the entire capitulum the top two species were the ox-eye daisy, Leucanthemum vulgare, with 15.9 ± 2μl, and Cosmos bipinnatus, which had a rate nearly equivalent to that of the corn poppy.

[16] The living flower made its European debut in 1826, courtesy of Scottish botanist David Douglas, who collected various plant seeds, including Eschscholzia californica, for the Royal Horticultural Society of England.

[16] While evidence indicates that the golden poppy started appearing in British gardens over the subsequent fifty years, it had not yet become strongly associated with ideas of California identity and statehood.

[16] An 1883 Scottish report, recounting a visit to California and an encounter with the golden wildflowers, reflects the early attitudes forming around the poppy.

[17] The Native Daughters and Sons of the Golden West played a pivotal role in establishing the California poppy as a cultural icon.

[17] In Waa'aka', the final plant created by the Tongva's god of creation, Wiyot, was the Island poppy, described as "golden as the sun, bringing beauty to the world.

The following cultivars have gained the Royal Horticultural Society's Award of Garden Merit:-[23] California poppies are commercially sold and widely naturalized in Australia, including Tasmania, and the species has also been introduced to South Africa, Chile, New Zealand, and Argentina.

[27][28] In this era, the state aimed to construct an external identity grounded in the natural wealth of the region, enticing newcomers and businesses with promises of celebration and prosperity.

[17] In the aftermath of the 1906 San Francisco earthquake and fire, the California poppy became a central design motif and symbol influencing various decorative objects.

The most popular sightseeing spot, Walker Canyon, was overwhelmed by more than 100,000 visitors in the span of a few days, causing city officials to temporarily shut down surrounding roads to motor vehicles.