The status of these lovely wildflowers is rather dismal. They are surrounded by buildings in a rapidly growing area zoned for industry and shopping centers. Some of the vernal pools have been damaged by deep tire ruts and the dumping of debris. Raised topography (mounds) near vernal pools once supported burrowing owls. During years with sufficient rainfall, some pools are teeming with San Diego Fairy Shrimp (Branchinecta sandiegonenis).

The species of Brodiaea with hooded staminodes appears to be Coastal BTK (Brodiaea terrestris ssp. kernensis) and not B. jolonensis. There is certainly some variability in the flowers of this species in San Marcos. The notch in the anther connective tissue may be V-shaped, U-shaped or W-shaped, with a minute appendage at the base of the notch. No flowers have the distinctive dentate connective of Brodiaea terrestris ssp. terrestris in Monterey County.

The ovary color, general floral dimensions and vascular pattern of Coastal BTK are different from B. jolonensis in Monterey County. This is discussed in more detail by clicking the red B. jolonensis tab at the top of this page. The chromosome number is at least 36 or more, too high for typical B. jolonensis in Monterey County. Coastal BTK identical to the San Marcos population occur elsewhere in coastal San Diego County, including Otay Mountain. Chromosome counts of the Otay Mountain population are currently under investigation by Dale McNeal of the University of the Pacific . Although no exact numbers have been determined at this time, preliminary studies indicate that the number may be higher than determinations made by Theodore Niehaus for Otay Mesa.

Two additional species of Brodiaea occur in the San Marcos field, including B. filifolia and B. orcuttii. The latter species generally occurs in the vernal pools, but may also grow intermixed with B. filifolia and Coastal BTK throughout the property.

Coastal BTK in the San Marcos population have distinctly hooded staminodes and anthers with generally 98% or higher pollen viability. These flowers would be considered fertile under Benson's criteria (1962). Smaller flowers with strap-shaped staminodes occur sparingly in the population. These flowers are sterile and their anthers contain no pollen grains. They appear to be sterile hybrids, possibly between Coastal BTK and B. filifolia or B. orcuttii. B. filifolia even appeared in a flower pot with corms of the transplanted hybrid. According to Niehaus (1971), hybridization occurs within sympatric populations of Brodiaea species. The progeny of these hybrid crosses generally have sterile flowers with no pollen. Hybrids can multiply asexually by cormlets. In addition, the field also contains a fertile hybrid between B. filifolia and B. orcuttii.

One possible explanation for hybrid sterility may be synaptic failure at prophase I of meiosis. Niehaus (1971) studied several populations of "Brodiaea jolonensis" in southern California and published sporophyte chromosome numbers of 36. We are certain that these populations are Coastal BTK and not B. jolonensis. My tentative count for Coastal BTK in San Marcos is at least 36. If these populations are hexaploid (6n = 36) with a base number of 6 (n = 6), a cross between a tetraploid (4n) BF (or BO) would result in a 5n (pentaploid) hybrid. Preliminary chomosome counts of Coastal BTK from Otay Mesa by Dale McNeal at University of the Pacific (personal communication, 2006) indicate that the number may be greater than 40. An exact count is difficult because small chromosomes are often obscured by larger ones.

With base numbers of 6 and 8 chromosomes, most species of Brodiaea are technically polyploids with multiple sets of chromosomes. For example, B. terrestris ssp. kernensis in Kern County is an octoploid with eight sets of chromosomes, and B. orcuttii is tetraploid with four sets of chromosomes. [B. jolonensis in Monterey County is diploid with two sets of chromosomes.] According to Niehaus (1971), the lack of quadrivalents in meiosis plus the differences in size of individual mitotic chromosomes at different ploidy levels suggests that these are "old polyploids." That is, the tetraploids, hexaploids, and octoploids have been in existence long enough to change by translocations, deletions, and so on. These differences apparently are enough to ensure that during meiosis only bivalents will occur in the higher ploidy levels. In bivalents, only two sets of maternal and paternal chromosomes associate during synapsis of meiosis, in contrast to quadrivalent where four sets of homologous chromosomes associate during meiosis.

If Brodiaea species behave as diploids, then BF and BO each have n = 12 and 2n = 24, and BTK has n = 18 or a higher number. In fact, BTK could be 2n = 36, 38, 40, 42, 44, 46, 48, etc. and still be theoretically fertile with two sets of homologous chromosomes. A hybrid between BF or BO and BTK would be sterile because of the non-homologous pairs of chromosomes that differ in number. Hybridization may occur, but the resulting hybrid offspring grown from seed may by sterile without viable pollen. For example, a cross between BF and BTK could result in a hybrid with 12 BF chromosomes and 18 BTK chromosomes which would not match up during synapsis of prophase I. This hypothesis is a plausible explanation for the sterile hybrids we have observed in San Marcos.

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