Coast Woolly Heads

Coast woolly heads (Nemacaulis denudata) is a California native, one of the few adapted to the hot, dry, windy, salty coastal strand environment. Unlike its neighbors, such as beach primrose and sand verbena, which celebrate another year of life with a vibrant display of spring color, coast woolly heads remains small and inconspicuous, hugging the ground and blending in against the sandy background. Tiny flowers occur in small hemispherical clusters, widely spaced along horizontal, thread-like stems. The plant looks somewhat like the remains of a messy sewing project.

Coast woolly heads is listed by California Native Plant Society as rare, threatened or endangered, not only because of habitat loss but because of inadvertant damage by foot-traffic.

The common name comes from the dense mass of long, woolly hairs that surrounds the flowers in the rounded clusters.

Description ^{2,11,34,59,306}

Coast woolly heads is a delicate, low growing plants from a taproot. There is a small basal rosette of sessile leaves, up to three inches (8 cm) long, linear to spoon shaped, with conspicuously crinkled margins. Leaves are made gray by a dense coating of long white hairs; older leaves become reddish.

Long, smooth, thread-like flower stems grow horizontally along the sand, branching occasionally. Flower stems are reddish in color and leafless. Tiny flowers occur in semi-spherical clusters (glomerules) along the stem, well separated from one another; often at a branching point in the stem. Small, thick bracts encircle the base of a cluster. Bracts are oval, about 1/4 inch (0.5 cm) long, red or green or green-tinged-red on the outer (lower) surface. The inner surface is densely covered with long, woolly hairs, which seem sticky – or exceptionally grabby – and which encircle the individual flowers. There are a few to many tiny, symmetrical flowers in a cluster. Sepals and petals are indistinguishable (sometimes together called “tepals”). There are six white to pinkish tepals, bell shaped when open. Flowers are bisexual, usually reported to have only three stamens, but occasionally, as seen in the image below, having four.³⁴ Anthers are bright red, and there is one inconspicuous pistil with three styles. Coast woolly heads blooms March – August.¹

The dry tepals persist around the developing fruit. The fruit is about 1/16 inch (1 mm) long, dry, shiny black, a flattened ovoid with a strongly pointed end; it contains a single seed and does not split open when mature.

Classification ^2,11,44,143

Coast woolly heads is a dicot angiosperm in the buckwheat family (Polygonaceae).² In this family, leaves are generally simple (not divided into leaflets) and alternate. Typically, flowers are tiny, symmetrical and clustered close together; sepals and petals are indistinguishable (called tepals), in two whirls of tepals, often three to six. Fruit is usually small, dry and one-seeded.

Other familiar species in the buckwheat family include rhubarb and sorrel as well as true buckwheat, which is a Eurasian species,¹¹ and California buckwheat (Eriogonum fasciculatum) which is common in the coastal sage scrub vegetation in the Reserve.⁴⁸

Nemacaulis has only one species, N. denudata with two varieties.² Varieties are distinguished by different ecological habitats and by morphological differences in the flower. The variety in the Reserve is variety denudata.

Ecology ³⁰⁶

The tepals of coast woolly heads are not shed from the flower, instead, drying to a loose papery envelop around the developing fruit. When seeds are ripe, the entire cluster is shed from the plant to be dispersed along the sand by sea breezes, effectively transporting several tiny seeds. If the cluster becomes trapped in a moist pocket of sand, several seeds are simultaneously planted in a favorable location. It seems likely that the tepals also catch blowing grains of sand and help bury the seeds. This maybe an effective method of seed propagation in a very harsh environment.

Human Uses  

It seems unlikely that any plant could be so insubstantial and inconspicuous as to escape the notice of the local Native Americans and subsequent human populations, but coast woolly heads appears to have done just that.

Interesting Facts  

Before Coast Highway, the entire area between Cardiff by the Sea and Solana Beach was sand dunes, long destroyed by human activities. In 2016 the California Wildlife Conservation Board awarded $850,000 grant to Nature Collective for a cooperative project to implement coastal wetlands restoration programs. This included the experimental re-creation of a dune area on a small portion of South Cardiff Beach, Seaside Terraces, immediately across Coast Highway from the Reserve. Sometime in the past, this new dune area was an old parking lot or roadway, and at the time of restoration, pieces of broken asphalt emerged from the sand, creating a safety hazard and public eyesore.

In late spring 2016 beach-quality sand removed from the San Elijo inlet as a part of the annual inlet dredging was mounded on the new dune site. The following winter, volunteers planted the new sand with one gallon dune plants of sand verbena (Abronia umbellata), and three endangered species: Nuttall’s lotus (Acmispon prostratus), Orcutt’s pincushion (Chaenactis gabriuscula var gabriuscula) and coast woolly heads. By May, the results were amazing. Beach primrose, another welcome dune plant, had made its way to the area and was in full bloom, along with sand verbena and Nuttall’s lotus; the thread-like stems of coast woolly heads criss-crossed the bare sand, making it difficult to step.

We will continue to monitor the site, keeping it clear of non-native competitors and, with the help of local visitors, free of foot traffic.