Chlorogalum as treated traditionally is a genus of 8 taxa endemic to the California Floristic province, extending in the north from its northern limit near Myrtle Creek, Josephine County, Oregon southward to far northern Baja California. Four of the 8 taxa are rare
The genus clearly consists of two distinct elements: three pale to deep purple flowered, diurnal taxa
n = 30 Chlorogalum purpureum Brandegee var. purpureum
n = ??? Chlorogalum purpureum var. reductum Hoover
n = 30 Chlorogalum parviflorum S. Watson
and 5 white flowered, verpertine taxa
n = 17 Chlorogalum angustifolium Kellogg
n = ?? Chlorogalum grandiflorum Hoover
n = 18 Chlorogalum pomeridianum (DC) Kunth var. divaricatum (Lindley) Hoover
n = 18 Chlorogalum pomeridianum var. minus Hoover
n = 15, 17 Chlorogalum pomeridianum var. pomeridianum
In 1940, Hoover (1) did not know of the tetrapolid nature of the two n=30 species, C. parvifolium and C. purpureum; he did remark on the floral differences. Cave (2) then documented chromosome numbers in the genus, postulating they represented a distinct clade and noted their karyotpyic links with Hastingsia alba. Now, Halpin (3) has shown that the diurnal-flowered plants are not monophylletic within Chlorogalum.
In my estimation, Chlorogalum purpureum and C. parviflorum ought to be segregated within a new genus. The name Hooveria is available for these plants, and would be a fitting tribute for Robert Francis Hoover, one of California’s most able field botanists.
1. Hoover, RF 1940 Madrono 5:137-147
2. Cave, MS 1970 Univ. Calif. Pubs. Bot. 57:1-51
3. Halpin, KM. 2011. Thesis, Oklahoma State Univ. 103 pp.