Land and Flora
A study of all rare and endangered plant species on the ranch was performed by Catherine Coe in 1990. An inventory was taken of the species identified and their location on the property. Listings were taken from the California Natural Diversity Database (NDDB) and the Native Plant Society (NPS). Further botanical research has identified two new species of manzanita that are endemic to the ranch, one of which is soon to be federally listed, and two species of clovers also endemic to the watershed; these discoveries were made by botanist, Jim West. The inventory of Swanton's rare and endangered plant species and other species that might be found on the ranch is available on the Plant List.
The majority of rare and endangered plant species identified are located on the northwest corner of the ranch. This is the area northeast of the schoolhouse and on the northern boundary to the west of Swanton Road. Many species show limited occurrence based on Coe's maps. The largest distribution of any one species is the Monterey pine (Pinus radiata). The northernmost stand of this species is located east of point Año Neuvo and it has a range of only about 130 miles south and usually within 7 miles of the ocean. While these trees are not currently listed as endangered, many have been infected by pitch canker and the removal of infected trees has been undertaken.
The most diverse communities of native plant species exist within the grass rangelands. Careful livestock management and rotational grazing practices promotes plant's healthy regeneration. Some exotic species found on the ranch, such as periwinkle and pampas grass, are invasive, thus affecting native species. For this reason, invasive species are actively controlled and eradicated.