Beach Primrose

Only a few plants can survive the harsh conditions of the coastal strand – the shifting, blowing strip of beach and sand dunes above the high tide line. This environment has been badly disturbed by development and recreational activities, and many of the coastal strand species have been declared threatened or endangered. In the Reserve, remnant coastal strand habitat persists in West Basin, between the railroad tracks and coast highway.

The beach primrose (Camissoniopsis cheiranthifolia ssp. suffruticosa) is one of our few coastal strand species. A dense covering of pale hairs protects it from the hot summer sun and a deep taproot and low-growing form anchor it against wind and shifting sand. In March and April, the yellow blossoms paint West Basin with bright stripes and patches.

Description ^{2,3,4,11,26,59}

Beach primrose is a low-growing, short-lived perennial subshrub that may form dense mats in sandy areas along the upper beach. A taproot gives rise to a basal rosette of obovate to oblanceolate leaves and several wiry stems that hug the ground, curling up at the tip. Green stems turn reddish with age. Leaves are variable; basal leaves may be as long as 3 inches (8 cm); cauline leaves become progressively shorter and wider toward the stem tip; they often lack a petiole and clasp the stem directly. The leaves of our plants generally have smooth edges, but leaves have also been described as wavy,⁵⁹ or minutely toothed.⁴ Leaves and stems are more or less heavily covered with dense pale hairs.

Bright yellow flowers are produced in leaf axils near the terminal ends of the stems. Flowers are bisexual, radially symmetrical and usually 1 to 1.5 inches (22-37 mm) in diameter with four fan-shaped petals. A petal may have one or more red dots at its base. The four sepals are bent backwards and often joined in pairs. There are eight stamens, of unequal lengths; these are shorter than the pistil which has a long style capped with a spherical stigma. Aging blossoms turn an orange color. The main bloom period is April, but flowers may be found between February and August.¹

The ovary (and subsequent fruit) is below the flower and looks like the flower stalk (it is “inferior”). The fruit is a slim, four-sided capsule that coils once or more. The dried capsule splits open at the end allowing the seeds to be dispersed by gravity and animals. Dried capsules persist on the plant after splitting.

Classification  

Beach primrose is a dicot angiosperm, which, in spite of its common name, is not a member of the primrose family (Primulaceae) but the evening primrose family (Onagraceae).²

Plants in the evening primrose family are characterized by radial, bisexual flowers with parts in multiples of four  (4 petals, 4 sepalsand 8 stamens).^2,11,59,143 Other members of this family found in the Reserve include the delicate canyon clarkia (Clarkiaepilobioides) and the robust Hooker’s evening primrose (Oenothera elata ssp. hirsutissima).

Beach primrose was originally placed in the genus Oenothera. Along with several other species, they were moved into a new genus, Camissonia, on the basis of the structure of the stigma, which is spherical in Camissonia and X-shaped in Oenothera, and also by the fact that flowers of Camissonia open in daytime, rather than evening.⁵⁹ Recently Camissonia was further split and beach primrose was moved to Camissoniopsis.

Two other species of Camissoniopsis have been reported from the Reserve: California suncup (C. bistorta) and Lewis’ evening primrose (C. lewisii).⁴⁸

Two subspecies have been described for C. cheiranthifolia.^2,7 Ours is ssp. suffruticosa.⁴⁸ The second, ssp. cheiranthifolia, has smaller flowers, a shorter style with the stigma surrounded by anthers, and a distribution both north and south of the range of ssp.suffruticosa. The divergence of ssp. cheiranthifolia from ssp. suffruticosa is thought to have been associated with a change in pollination from insect-pollination (in ssp. suffruticosa) to self-pollination (in ssp. cheiranthifolia).^163,164 This differentiation was accompanied by a change in flower morphology. Flowers of ssp. cheiranthifolia are smaller and paler, making them less visible to pollinators; the stigma is surrounded by the anthers, which facilitates self-pollination. It is postulated that the beach environments of  ssp. cheiranthifolia may be more variable and/or more extreme, making insects less reliable as pollinators.

Ecology ^165,166,167

Beach primrose is adapted to the coastal strand habitat of the upper beach and dunes. This is one of the harshest environments on earth. Plants must survive toxic salt spray, wind and sand scour, shifting substrate and the scorching temperatures of sand under summer sun. Both nutrients and water are scarce. Beach primrose is one of the few plants that thrive in the coastal strand environment.

Like most strand plants, beach primrose has a long taproot to anchor itself and numerous horizontal, radiating branches to hold the sand beneath. Leaves are small and densely covered with white hairs to reduce water loss and to reflect the summer sun. Growth and reproduction occurs during and following the winter rains and the plant is dormant during the hot, dry months of summer.

Human Uses  

Beach primrose is recommended for native plant gardens, especially in sandy soil.⁷⁹ Given a bit of summer water, it may flower all year.¹⁶⁸ It is often used in dune restoration work.²³

Interesting Facts  

Before the railroad and Coast Highway were built, the mouth of San Elijo Lagoon moved between the bluffs of Solana Beach to those of Cardiff-by-the-Sea. It was a dynamic environment, pounded by surf, blown by wind, and periodically flooded with freshwater from upstream. Much of the entrance was often closed by sand, and the estuary opening wandered, breaking through sand dunes at various places at different times. It was a functioning coastal strand environment, supporting a few highly adapted species of plants and animals. Unfortunately, the berms supporting the railroad and Coast Highway blocked the energy of wind and waves, and other plants became established in the less dynamic, more stable environment, crowding out the native vegetation. Coastal strand habitat began to disappear.

Nature Collective is restoring a remnant of this rare coastal strand environment. While the full dynamics of dune habitat can not be recaptured, management of non-strand vegetation will allow the original species to recover. A four acre site in West Basin has been fenced off to limit foot and vehicular traffic. Much of the site has been cleared of desert arrowweed (Pluchea sericea), a plant that is native to California desert environments but thrives in relict coastal strand habitats where it is protected from the scouring activity of wind and waves. Non-native invaders, such as ice plant (Carpobrotus edulis), statice (Limonium sinuatum and L. perezii) and sea rocket (Cakile maritima) are being controlled. Beach primrose populations are thriving, along with sand verbena (Abronia umbellata var. umbellata), and there are recovering populations of three endangered dune species: Orcutt’s pincushion (Chaenactis glabriuscula var. orcuttiana), Nuttall’s lotus (Acmispon nuttallianus) and coast wooly-heads (Nemacaulis denudata var. denudata).