Rare Plants: Calochortus catalinae (CNPS-CI)


CALIFORNIA NATIVE PLANT SOCIETY Channel Islands Chapter
Rare Plant Profiles: Calochortus catalinae
Description Calochortus catalinae S. Watson, Catalina Mariposa Lily, is a bulbiferous perennial herb in the Liliaceae (Lily family). It has bulblet-bearing stems 20 to 60 cm long, with withering basal leaves from 10 to 30 cm. The inflorescence consists of 1 to 4 erect, bowl-shaped flowers with purple-spotted (near base) sepals (20 to 30 mm) and white, tinged lilac, purple-spotted, nearly glabrous (hairless) flowers. The flowers include oblong, densely branched, hairy nectaries (not depressed), and erect non-angled fruit (2 to 5 cm). Calochortus catalinae blooms between February and May. Calochortus catalinae can be easily confused with Calochortus venustus; however, the later has colored spots that occur towards the tip of the petals, where the spots are only found near the base in C. catalinae. Habitat and Distribution Calochortus catalinae is an uncommon herb of heavy soil (loamy clay to clay loam) in open grassland, coastal scrub, and chaparral habitats and is known below 700 meters in elevation. It occurs primarily in the southern portion of the Central Coast and the western South Coast, and is known in Santa Barbara, Ventura, Los Angeles, Orange, and San Bernardino Counties (including Santa Catalina, Santa Cruz, and Santa Rosa Islands). It has also been reported in San Luis Obispo County; however, that occurrence has been extirpated. Undocumented, doubtful, or unsubstantiated reports elsewhere include Santa Diego County reports, and plants grown in botanic gardens. Calochortus catalinae is sometimes observed on various slopes, primarily associated with Coastal Sage Scrub vegetation. It is locally common at many of its occurrences, particularly in Coastal Sage Scrub habitats. Calochortus catalinae contributes to the ground layer, growing below the intermittent shrub canopy along with the following common associates: Bloomeria crocea (Goldenstars), Calystegia macrostegia ssp. cyclostegia (Morning-glory), Calochortus clavatus ssp. clavatus (Club-haired Mariposa Lily), Castilleja affinis ssp. affinis (Lay-and-Collie Indian Paintbrush), Nassella [Stipa] pulchra (Purple Needlegrass), and Silene laciniata ssp. major (Mexican Pink). The predominant Coastal Sage Scrub shrub species include: Artemisia californica (California Sagebrush), Baccharis pilularis ssp. consanguinea (Coyote Brush), Encelia californica (California Bush Sunflower), Malosma laurina (Laurel Sumac), Salvia leucophylla (Purple Sage), and Hesperoyucca whipplei (Our Lords Candle). Below are maps of known populations of Calochortus catalinae in the Channel Islands Chapter area (Santa Barbara and Ventura Counties), and a map of all collections of natural occurrences with the areas occupied delineated in three coloers (magenta for extant occurrences, yellow for occurrences of unknown condition, and gray for extirpated occurrences). Undoubtedly, there are more populations out there within this species' range; however, they are not supported by voucher specimens that have been deposited into public herbaria. A few collections reported but not mapped here represent either misidentifications or cultivated plants at botanic gardens. The lone San Luis Obispo collection, from Pismo Beach, was from 1934 and the plant has not been found in San Luis Obispo County since. Based on this assessment, there are 216 documented occurrences, of which 125 are presumed extant, 27 extirpated, and 64 of unknown condition. The 125 extant occurrences represent approximately 95 populations, using the California Department of Fish and Game's Natural Diversity Database population criteria. The occurrences of unknown condition represent an additional 59 populations, presuming they are all extant. Rarity Status/Rankings G3 = Rare and local throughout range or in a special habitat or narrowly endemic (on the order of 21 to 80 occurrences) globally N3 = Rare and local throughout range or in a special habitat or narrowly endemic (on the order of 21 to 80 occurrences) in the United States S3.2 = Rare and local throughout range or in a special habitat or narrowly endemic (on the order of 21 to 80 occurrences) in California CNPS List 4.2, Plants of Limited Distribution, fairly endangered in California Calochortus catalinae is threatened by development, both for urban and agricultural land uses. Based on the known number of extant populations, and the likelihood that at least some of the occurrences of unknown condition are in fact extant, the rarity rankings for this species should be changes from G3, N3, and S3 to 4 since there are 95 known extant populations with up to another 59 populations on unknown condition. Historical losses from development (urban and agriculture) represent at least 12.5 percent.
CHANNEL ISLANDS CHAPTER, CALIFORNIA NATIVE PLANT SOCIETY, PO Box 6, Ojai, CA 93024-0006 Special thanks to Carlin Moyer for the beautiful illustrations on our site. Photographs and maps are by David Magney.

Created: 5 September 2008; Last updated: 9 June 2010 For website comments: webmaster(at)cnpsci(dot)org
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