Plants spotted by Dylan Neubauer. Keyed to T. oliganthum in both TJM2 and draft of the recent Trifolium key by Randy Morgan (which includes a number of newly discovered and/or circumscribed taxa not in TJM2). There are a number of notable items here:

1) T. oliganthum was not recorded in the 1990 Flora of the San Bruno Mountains by McClintock, Reeberg, and Knight. 2) T. oliganthum did not appear on the NRBD San Bruno Mountain list retrieved on 2/17/14. 3) The closest station given in the Checklist of the Vascular Plants of San Mateo and Santa Clara Counties is at Jasper Ridge, 22 air miles to the south. 4) This sighting appears to be early in flowering phenology...which may account for it's relatively diminutive size; single inflorescences per stem; and very few-flowered heads with reduced-size involucres.

This is among the most inconspicuous of Trifolium species, and is easily overlooked. So it may be present, but unrecorded, in other locales. Nonetheless, the above info is of interest.