The rediscovery of Arctostaphylos franciscana Eastw. [A. hookeri G. Don ssp. franciscana (Eastwood) Munz ] right in the path of a critical highway project and news reports of what is planned to mitigate the problem have not mentioned one critical factor: buried viable seed. Buried seeds are genetic individuals, and take under the endangered species act can be extended to include any removal of individuals from the gene pool. If we mitigate the problem only by propagation, and later planting ex situ, a take will occur because unique genotypes that exist only as buried viable seed will not be provided for.
It might seem a little fishy that the prior known sites for A. h. ssp. franciscana were on serpentine on Mt. Davidson, while the Doyal Drive site is (probably) on stabilized dunes (?), but both A. hookeri ssp. franciscana and A. h. ssp. ravenii Wells were once sympatric on Mt. Davidson (Roof, 1976 Four Seasons Vol. 5) whereas now both are reduced to single remnant individuals on non-ultramatic substrata. The substrate character of the Arctostaphylos hookeri ssp. franciscana site is relevant: buried viable seed might be well distributed both horizontally and vertically over a considerable distance about the newly discovered single bush if in fact the soils there are loose or sandy, and even if the soils are not sand, buried seed is someplace out there and vulnerable.
In order to fully mitigate potential impacts to Arctostaphylos hookeri ssp. franciscana, a program of salvage intended to capture buried viable seed will be required. Yes, it sounds nuts, but soil excavation and processing should be conducted. Volumes of soil excavated from the site need to be trucked to a experimental site, aliquots inspected directly for seeds, while the bulk needs to be processed to induce germination. How to do this: conduct research. Should the soil be cold stored until the research indicated how to proceed? Should the soil be mechanically scarified? Fire simulated? Again, conduct research.
A billion dollar highway project is not likely to be halted in spite of the rediscovery of an 'extinct' plant, but a fraction of the cost needs to be diverted to the conservation of the Franciscan Manzanita. A stimulus plan to gain a better understanding of manzanita biology is needed.