Coast Woolly Heads

Nemacaulis denudata

green base with red branches
Seaside Reef | May 2017

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.

Other Common Names:

woolly heads, cottonheads, coastal woollyheads

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.

base of plant coming from ground
finger holding tiny green flowers
Three flower clusters | April 2015
microscopic view of bundle of green flowers
Flowers in clusters showing red anthers (here, 4) | May 2015

Distribution 7,89

Coast woolly heads is native to southern California, western Arizona, northern Baja California and northwestern Sonora Mexico. There are two disjunct populations, with some overlap. These are recognized as different varieties. One variety, var. denudata, is a coastal species of beaches and dunes; the other, var. gracilis tends to occur in the desert. Both grow primarily below 3000 feet (1000 m).

Coast woolly heads is classified as rare, threatened or endangered in California and elsewhere (1B.2).45 It is currently known from only 37 locations. Habitat has been lost to coastal development, and the delicate plants are displaced by non-native species and easily destroyed by foot traffic.

In the Reserve, coast woolly heads are found only in the small dune area in West Basin, between the rail road and Coast Highway. This area is not open to the public. They are also now found in a site across Coast Highway from the southern portion of West Basin where funding to SELC from the state Wildlife Conservation Board has permitted cooperative dune restoration at the Seaside Dunes.

Reserve map of chaparral, coastal sage scrub and grassland

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.

Jepson eFlora Taxon Page
microscopic view of seed
One seeded fruit | Seaside Reef | June 2017
close up of think sticks interlocked with white flower pods
Flower stems | May 2012
overview of wire like plant

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.

cluster of white and red flowers
Flower cluster | Seaside Reef | May 2017
microscopic view of single flower pod
Tepals around ripening fruit | Seaside Reef | June 2017
overhead view of thin stick plant
Seaside Reef | June 2017

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.

succulent type base with long string stems
two bushes of green leaves on ground
Seaside Reef | May 2017
pod of white, red and green tinted flowers on stick

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 the San Elijo Lagoon Conservancy 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.

Woman walking on the sand covered in pink and yellow flowers
Intern helps volunteers remove the non-native sea rocket from the new dune site | Seaside Reef | May 2017
Small branched out stems with yellow flowers
Young beach primrose, sand verbena, and coast wooly heads on the new dunes | Seaside Reef | May 2017
Sand covered in small red flowers and tangled stick-like stems
Coast wooly heads were reestablished at seaside terraces Dunes | Seaside Reef | May 2017

Photo Gallery

Bracts below flower cluster | Seaside Reef | June 2017
Single bract | Seaside Reef | June 2017
Single bract | Seaside Reef | June 2017
Coast Wooly Heads
Seaside Reef | May 2017
Coast Wooly Heads
Seaside Reef | May 2017
Intern helps volunteers remove the non-native sea rocket from the new dune site | Seaside Reef | May 2017
Young beach primrose, sand verbena, and coast wooly heads on the new dunes | Seaside Reef | May 2017
Coast wooly heads were reestablished at seaside terraces Dunes | Seaside Reef | May 2017
Seaside Reef | May 2017