Finding Rare Treasures at Our Feet in Point Reyes' Coastal Dunes

By Plant Community Monitoring Technician Arturo Aguilar, San Francisco Bay Area Inventory & Monitoring Network

Each summer, the Plant Community Monitoring team catalogs vegetation diversity and structure in San Francisco Bay Area national park plant communities. This summer, we spent a month of field work surveying coastal dune scrub at Point Reyes.

NPS / Arturo Aguilar

August 2025 - Warm sand under boots; a coastal breeze blowing through; the sounds of waves crashing on a distant beach. What might sound like a dream vacation was actually the average June workday for the San Francisco Bay Area Inventory & Monitoring Network’s Plant Community Monitoring (PCM) team. Even with spectacular seaside views, we were distracted by comparatively inconspicuous treasures right by our feet. A collection of rare plants sparked our excitement and drove unending questions.

Each summer, the PCM team catalogs vegetation diversity and structure in San Francisco Bay Area national park plant communities. This summer, we spent a month of field work surveying the coastal dune scrub community at Point Reyes National Seashore. During these monitoring surveys, the crew records the status of all plants present in the community. Often, this involves quantifying the coverage of common grasses and shrubs. But along the way, we occasionally document rare plant occurrences too.

Full of rare species

In some cases, the PCM team only encounters rare species after meticulous searching. Such was the case with the short-leaved evax (Hesperevax sparsiflora var. brevifolia), a miniature member of the sunflower-family (Asteraceae) that we found beneath the shadow of a coyote brush. In another instance, we found another rare plant, the woolly-headed spineflower (Chorizanthe cuspidata var. villosa), carpeting large swathes of dunes. Sometimes it seemed like the only truly rare sight was a spot in the sand free of their piercing, spine-laden flowerheads.

Woolly-headed spineflowers bear sharp spines surrounding groups of flowers.

© R.A. Chasey / mu33558 / 2023-06-18 / Calflora.org / CC-BY-NC 4.0

The abundance of different rare species had the crew asking all sorts of questions as we trudged through sand and scrub. In particular, what was it that made dune ecosystems so full of rare species? And how could species with such vigorous local populations be considered rare? These questions, it turns out, can be answered by the challenging conditions that shape the dunes and their inhabitants.

Special adaptations required

In the dune ecosystem, diversity comes from adversity. The stressful conditions of poor nutrient availability, shifting successional states, and high salinity make it so that not just any plant can grow in the sand. As such, life in the dunes requires the special adaptions displayed by many of the rare plants encountered in the Point Reyes dunes. The reward for so much adaptation? Living where competition with other plants is far less intense compared to more hospitable environments.

The short-leaved evax is so small, it boasts the smallest sunflower-like flower known to scientists! Its diminutive stature is likely an adaptation for the nutrient-poor substrate it resides in. Dune soil, composed predominantly of sand and small amounts of plant material from previous generations, carries little of the necessary nutrients for robust plant growth.

With extremely small flowers, short-leaved evax stands only a few centimeters above ground.

© R.A. Chasey / mg157943 / 2022-03-20 / Calflora.org / CC-BY-NC 4.0

Its diminutive stature is likely an adaptation for the nutrient-poor substrate it resides in.

© R.A. Chasey / mg157943 / 2022-03-20 / Calflora.org / CC-BY-NC 4.0

Growing quickly and spreading like a mat are great adaptations for taking advantage of new real estate. That is exactly how the woolly-headed spineflower remains so prevalent in the dunes. While larger woody shrubs may live longer and cast more shade, they cannot respond to early successional opportunities as readily as spineflowers and plants with similar life histories. There’s so much open real estate on dunes because, as you may have experienced on a windy beach day, they have a propensity to shift. The gradual movement of sand imposes a perpetual cycling of succession, where bare ground free of plant growth is always found somewhere.

Woolly-headed spineflowers form sprawling mats across the dune sand to take advantage of the new real estate that becomes available as dunes shift.

© R.A. Chasey / mu33558 / 2023-06-18 / Calflora.org / CC-BY-NC 4.0

Nowhere else to make it

But being built for a specific ecosystem does have its drawbacks. Dune ecosystems themselves are imperiled by a myriad of human-caused impacts. Development along coasts, introduction of problematic non-native species, and rising sea levels have greatly constrained today’s range of intact dunes along the California coast. With such limited habitat, it’s no wonder so many rare plants are found in the dunes. They have nowhere else to make it! So even as species like spineflowers and evax are plentiful within their specialized habitat, it is the global rarity of that habitat that threatens their future.

The distinctive value of ecosystems like coastal dune scrub makes the work of plant community monitoring essential. In order to protect rare plants, we must understand the status of the communities they’re a part of.

For more information

• If you're interested in learning more about how the Plant Community Monitoring crew works and what we're learning, visit our website or contact Botanist Kelsey Songer.
• To learn more about rare plants at Point Reyes, visit the park's Threatened, Rare, & Endangered Plants webpage.

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