The Genus Eschscholzia

California Poppies and Their Relatives

The California State Flower

On December 12, 1890, the California State Floral Society voted to select a State Flower. The three nominees were Eschscholzia californica, the California poppy, Romneya coulteri, called giant poppy at the time, but now usually referred to as Matilija poppy, and Calochortus (no species indicated), the mariposa lily. The California poppy won by a landslide; only three votes were cast for Calochortus, and none for Romneya. The California poppy had been first described 70 years before, and it already had 64 years of horticultural history.

Taxonomic history of Eschscholzia

Although the California poppy had surely already been seen by Europeans, perhaps by members of the Cabrillo expedition in 1542, and almost certainly by the late 1700s, it was first described by Adelbert von Chamisso (1820) based on a collection from San Francisco in 1816. Chamisso was the naturalist on the Russian ship Rurik, captained by Otto von Kotzebue. The Rurik landed in San Francisco in October, and the California poppies were among the few plants still in flower. Chamisso named the genus in honor of Johann Friedrich Eschscholtz, the expedition's physician and Chamisso's close friend.

Fifteen years later, four species were added to the genus by the English botanist George Bentham: E. caespitosa, E. tenuifolia (now included in E. caespitosa), E. hypecoides, and E. crocea (now included in E. californica). Two additional species, both now included in E. californica, were described during the next decade, and Sereno Watson described E. minutiflora in 1876.

The greatest taxonomic impact on the genus came from Edwin Lee Greene, first botanist at the University of California. Greene was a taxonomic "splitter" who believed in the fixity of species. It was rumored that he could collect material from a plant, name it a new species, return to the site later in the same season, unknowingly collect from the same plant, and name it a different species. Greene's views on the relative importance of similarity and difference can best be seen in the introduction to his 1905 revision of the genus:

As to the powers of taxonomic discernment, there are a few who, having before them several related plants, can see, and do see, of their own discriminative intelligence, the differences that separate them.

There is a much larger class of those who, in the same case, seem blinded by the resemblances which these related things so strongly bear to one another, and cannot see the differences at all distinctly until some other has pointed out those differences one by one. Then, these too can see.

There is a third class, consisting of such as can not [sic] see a thing that is before their eyes and has been pointed out. [p. 209]

Greene named a total of 116 new species, subspecies, and varieties in Eschscholzia. Of these, eight are still recognized (E. californica ssp. mexicana (Greene) C. Clark, E. parishii Greene, E. minutiflora ssp. covillei (Greene) C. Clark, E. glyptosperma Greene, E. rhombipetala Greene, E. lobbii Greene, E. ramosa (Greene) Greene, and E. elegans Greene); all the rest have been placed in synonymy with other species (Clark, 1979).

While Greene was naming new species, others were combining them. T. S. and Katharine Brandegee wrote a number of papers critical of Greene's taxonomic splitting. Later, Willis Linn Jepson, Greene's student and author of the first general flora of California (Jepson, 1922), only recognized eight species, and did not even bother to synonymize most of Greene's names.

Wallace Ernst addressed the taxonomy of the genus in his doctoral dissertation (1962), and later reassessed the Eschscholzia species in the south Coast Ranges (1964). My recent treatment of the genus in the new Jepson Manual (Clark, 1993) reflects the work of all these people along with my own studies (Clark, 1978a, b, c, 1979a, b, 1980, 1986, 1993; Clark and Charest, 1992a, b; Clark and Faull, 1989, 1991; Clark and Jernstedt, 1978; Clark and Webster, 1980; Jernstedt and Clark, 1978, 1979).