Sea Dahlia [Coreopsis maritima (Nutt.) Hook. f.]

Sea Dahlia [Coreopsis maritima (Nutt.) Hook. f.]

Listing CNPS List 2 R-E-D Code 2-2-1

State/Federal. Status None ASTERACEAE Mar.-May

Global Rank G3 State Rank S3.2

Distribution: San Diego County; Baja California, Mexico

Habitat: Sandstone cliffs near the ocean are the preferred microhabitat of Sea Dahlia. Presumably, the moist sea breezes are a significant factor in providing optimal habitat for this perennial with semi-succulent leaves and fistulous stems. Gaviota fine sandy loams are utilized at the Point Loma Subbase while the Torrey Pines population grows on Terrace Escarpment sandstones. Typically Sea Dahlia chooses highly eroding slopes where competition from other shrubs is limited. Herbivory may play a role in the precarious cliffside locales often utilized.

Known Sites: A stable population occurs at Torrey Pines Preserve. A smaller population is situated on steep east-facing cliffs at the Subbase on Point Loma. A very small relictual population is found on a sandy ridge north of the terminus of Swallowtail Drive in Encinitas. Approximately 150 shrubs grow in a highly eroded drainage on sea bluffs south of Shingle Bluff on Camp Pendleton. Sea Dahlia is uncommon in the Tijuana Hills near the ocean. This species occurs on Carmel Mountain on north-facing slopes near the quarry. Approximately fifty shrubs were observed on a steep west-facing slope immediately west of I-5 and north of Manchester Road in Encinitas; approximately 100 plants occur in the hills north of El Nido road in Rancho Santa Fe. Most historical sites in the County have been extirpated by construction of "ocean view" lots. A curious old report occurs inland on the north slope of a peak just east of the San Diego Aqueduct and north of Escondido Creek approximately 1 mile west of the southernmost dogleg of Harmony Grove Road. Other old reports are from Spooner's Mesa near the Mexican border, Oceanside, and at Cardiff. Old biological survey reports note sites at the seabluff at the western terminus of Border Avenue northwest of the Del Mar Racetrack, in the Crest Canyon drainage in Del Mar, in Goat Canyon near the Tijuana border, and west of Fourth Street in Del Mar.

Thirty-six specimens from Baja are found in the San Diego Herbarium; south to 30 31' North where collected by Moran (SD 84492) west of San Quentin. Numerous scattered, but vigorous populations are seen on rocky headlands along the immediate coast of northern Baja California from Rosarito Beach south to Punta Banda. Several plants grow on a rocky knoll well inland, near Rodriguez Dam east of Tijuana. This shrub occasionally occurs several miles inland, such as canyon tributaries of Guadalupe Valley, in locales which experience occasionally moist onshore winds.

Status: Sea Dahlia is substantially declining in San Diego County. Natural erosion on seabluffs and homes built yards to the east are not conducive to long term survival of this species. It may benefit from seeding or direct planting on sandstone bluffs overlooking the ocean within its historical range. All populations should be protected.

San Diego Sand Aster [Corethrogyne filaginifolia (H. & A.) Nutt. var. incana (Nutt.) Canby


Copyright May 1994 Craig H. Reiser.

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