Horkelia marinensis is a California endemic, endangered plant known from limited geographic regions along the California coast. At the southerly geographic extent, in Santa Cruz County, there are 5 extant occurrences known (and three other old records that have not been georeferenced).
This note reports that Horkelia marinensis is probably self-compatible. In 2005, I salvaged several plants that were being taken by instillation of a electrical transmission line pole. The site (JEPS109793) is at 2500 feet on Ben Lomond Mountain. The Horkelia occurrence here contained about 1000 plants, most of them growing in the road under the powerline for perhaps half a mile, the adjacent brush being very dense (see power line ROW)
All but one of the plants dug died, most of the plants I dug had large taproots and hence did not make it. The survivor, now 10 years old, is about one-half a meter in diameter and flowers nicely. Several years ago, seedlings from this plant began to grow in pavement and walkway cracks. This photo shows one on the side of the driveway. That plant is perhaps 5 years old now.
The apparent fecundity of this single individual of Horkelia marinensis suggests that it is self-compatible.
Two Santa Cruz county occurrences do not yet appear in NDDB
No. 1 UCSC8932 on a ridge draining to San Vicente Creek
No. 2 Moore Creek Greenbelt site, Santa Cruz