By Fred Roberts, Chairperson Rare Plants Committee

Following up on a piece I wrote last summer (Rare Plant Hunting in a Dry Year, CNPS San Diego Chapter Newsletter, August 2018), I wanted to report on one of the species mentioned, Munz’s mariposa lily (Calochortus palmeri var. munzii, right), a California Rare Plant Rank 1B.2 plant. As I related last summer, in early June 2018, Jenny Moore, at the time the staff botanist for the Cleveland National Forest, had found an interesting mariposa lily near Buckman Springs south of I-8. It certainly looked a good deal like splendid mariposa lily (Calochortus splendens) but something was off and she wondered if it represented a hybrid 8 (you can see Jenny’s original plant on iNaturalist, it is the only record oniNaturalist south of I-8).

I’ve been looking for this species in San Diego County for about seven years so when she sent me her image that clearly showed yellow hairs at the base of the petal, not white, I knew exactly what it was (interestingly, there was a parallel conversation in the comments under her iNaturalist post where the commenters had come to the same conclusion). Jenny took me to the site in the first week of July 2018. Unfortunately, the plants were not in the best condition and there were too few plants present to collect a voucher specimen. We vowed to follow-up on this rare plant in 2019.

I’ve been quite interested in this plant as it occurs in San Diego County. When it first was added to the San Diego plant lists, it was known from about a half dozen sites, and with the exception of two collections from the Chihuahua Valley and near Warner Springs from 2010 and 2009 respectively, all the collections were old. It was almost absent from the San Diego Plant Atlas. Clearly it was not an abundant plant.