The Soap Plants, Soaproots or Amoles are the genus Chlorogalum of flowering plants. Less common names for them include Soap Lilies. They are endemic to western North America, from Oregon to Baja California, and are mostly found in California.

The Soap Plants grow as perennial plants, from a bulb, more or less elongated depending on the species. The bulbs can be white or brown, and in most species are very fibrous. The leaves grow from the base of the plant. The flowers are born on a long central stem, and appear to have six rather separate petals (not all are petals in the technical sense). There are 6 stamens, which are rather prominent in most species.

The placement of the genus Chlorogalum is currently uncertain. Until the 1980s, it was generally treated in the Lily family, Liliaceae, in the order Liliales, and conservative taxonomic sources such as ITIS still put it there. The consensus of more recent classifications has been that this is untenable, and for a time Chlorogalum was placed in the hyacinth family Hyacinthaceae, in the order Asparagales. According to Pfosser and Speta (1999), however, molecular systematics now shows that this placement too is wrong at the family level, though they confirm that the genus should be within the Asperagales. Pfosser and Speta conclude that, along with genus Camassia, Chlorogalum seems to be most closely related to the families Agavaceae, Funkiaceae and Anthericaceae. The emerging consensus seems to be that these two genera should be placed in an expanded Agavaceae.

Five species are currently classified in the genus. All except the Wavy-leafed Soap Plant, Chlorogalum pomeridianum, have rather restricted distributions, with little overlap. The Wavy-leafed Soap Plant, however, has a range that virtually encompasses those of all other members of the genus, and is commoner than any of them.

• Narrow-leaf Soap Plant, Chlorogalum angustifolium, found in the inner north Pacific Coast Ranges of California and southern Oregon and the Sierra Nevada foothills
  
• Red Hills Soaproot, Chlorogalum grandiflorum, found in the north and central Sierra Nevada foothills
  
• Small-flowered Soaproot Chlorogalum parviflorum, found in the south coastal region of California, south of Santa Barbara, and into Baja California
  
• Wavy-leafed Soap Plant, Chlorogalum pomeridianum, found anywhere in California except the Sierra Nevadas and the deserts, and also in south-western Oregon
  
• Purple Amole, Chlorogalum purpureum, found in the Outer South Coast Ranges of California, south of Monterey Bay and north of Santa Barbara

External links

• Genus treatment from the Jepson Manual (http://ucjeps.berkeley.edu/cgi-bin/get_JM_treatment.pl?8349,8521)
• Palomar College site on Soap Lilies in California (http://waynesword.palomar.edu/pldec198.htm)

References

• Pfosser, M. and Speta, F. (1999) Phylogenetics of Hyacinthaceae based on plastid DNA sequences. Annals of the Missouri Botanical Garden, 86, 852-875.