Hickman's potentilla

2007 Schools Wikipedia Selection. Related subjects: Plants

iPotentilla hickmanii
Hickman's potentilla. Photo credit: Tony Morosco
Hickman's potentilla. Photo credit: Tony Morosco
Conservation status

Endangered (EN)
Scientific classification
Kingdom: Plantae
Division: Magnoliophyta
Class: Magnoliopsida
Order: Rosales
Family: Rosaceae
Subfamily: Rosoideae
Genus: Potentilla
Species: P. hickmanii
Binomial name
Potentilla hickmanii
Eastw., 1900

Hickman’s potentilla (Potentilla hickmanii) is an endangered perennial herb of the rose family. This rare plant species is found in a narrowly restricted range in coastal northern California, primarily along a confined location of northern Monterey County, secondarily in extremely small colonies in San Mateo County and Sonoma County. This small wildflower, endemic to western slopes of the outer coastal range along the Pacific Ocean coast , produces bright yellow blossoms throughout the spring. The species is also known by the common name Hickman's cinquefoil.

This plant, along with many other threatened species in the northern California Floristic Province, has been designated as a species meriting protection by the U.S. Government, State of California, local governments and private conservation groups. These designations have led to blueprints for protection of Hickman's potentilla in the form of official endangerment classifications and a species Recovery Plan, the latter promulgated by the U.S. Environmental Protection Agency. Even with all these efforts, the total current population is estimated to be fewer than 4500 organisms.


Hickman's Potentilla is found on Montara Mountain below 135 meters in elevation, at the extreme east (right) of this image.
Hickman's Potentilla is found on Montara Mountain below 135 meters in elevation, at the extreme east (right) of this image.

Hickman’s potentilla is a rosetted non- glandular flowering plant with a thick taproot. It has a stem that is prostrate to decumbent, of variable length five to forty five centimeters, which may occur in a glabrous manifestation. Blooming occurs between April and June; in winter, the plant dies back enitrely, leaving only its woody stem intact. The hypanthium is three to six millimeters wide, with yellow obchordate petals six to eleven millimeters in length. Up to ten inflorescences may present in a single organism. Filaments are typically 1.5 to 4.0 millimeters in length, while anthers are only about one millimeter in size; moreover, the pistils generally number about ten and the slender styles are about two to three millimeters long.

The somewhat subglabrous leaves are pinnately compound into generally six paired, palmately cleft leaflets. These basal leaves range from six to twenty five millimeters in length with individual leaflets two to eight millimeters long and about two millimeters wide. There are four to seven leaflets per side, in a separated or overlapped configuration. The leaflets are wedge-shaped, typically having three to four teeth (lobes) and originate from about halfway along the leaf stem. The smooth fruits are approximately two millimeters in diameter, and normally occur as tan in colour.

Range and habitat

Coastal habitat near the vicinity of Vicente Creek, Moss Beach
Coastal habitat near the vicinity of Vicente Creek, Moss Beach

Hickman's potentilla is currently known to occur in three coastal locations. The Federal Register documents colonies on the Monterey Peninsula and at one site in San Mateo County and it is also known to occur on one site in northern Sonoma County. The Monterey population is within the municipal boundaries of the city of Monterey growing in fine sandy soils within an opening of pine forest that supports wet conditions for a variety of native and nonnative grassland species. The Monterey County population within the Del Monte Forest is the original discovery colony and numbers approximately 2000 plants.

A second coastal colony was discovered in Moss Beach, California in 1933 in a wetland area at the mouth of San Vicente Creek; this colony was presumed extirpated by at least the 1970s. Another population in San Mateo County was discovered in 1995 on the south slopes above Martini Creek ( USGS quad reference Montara Mountain 3712254), on private land by biologists conducting surveys for the Devil's Slide highway project. The Sonoma County population is situated in the Stemple Creek coastal watershed and is within USGS quad reference Two Rock 3812237. In all cases the populations are found between altitude 10 to 135 meters. The habitat for this species includes vernally wet meadows or open pine forests.


A point on the Monterey Peninsula, that Viscaino mapped
A point on the Monterey Peninsula, that Viscaino mapped

The Monterey Peninsula, discovery site of Hickman's potentilla, is recognized to have a high degree of species endemicism. Species with more northern ranges often reach their southern limits on the Peninsula; species with more southern affinities reach their northern limits there as well. The Monterey Peninsula is influenced by a marine climate that is pronounced due to the upwelling of cool water from the Monterey submarine canyon. Rainfall is 40 to 50 centimeters per year, but summer fog-drip is a primary source of moisture for plants that would otherwise not be able to persist with such low precipitation. Some taxa, such as the coastal closed- cone pines and cypresses are relict stands, e.g. species that once extended more widely in the mesic climate of the late Pleistocene period, but then retreated to small pockets of cooler and wetter conditions along the coast ranges during the hotter, drier early Holocene period between 6000 and 2000 BC}.

The first recorded history of the discovery site was in 1602, by the Spanish explorer Sebastian Viscaino, whose mission was mapping of the coastline. Viscaino noted in his journal the presence of "pine covered headlands...great pine trees, smooth and straight".

Alice Eastwood discovered P. hickmansii in the year 1900 on the Monterey Peninsula, a region then considered the fringe of civilization. The Big Sur wilderness lay just beyond, unpenetrated by any roads at that time. Eastwood, Curator of Botany at the California Academy of Sciences in San Francisco was a pioneer biologist in exploring this remote area. On an expedition to amass specimens of rare plants from this southern reach of Monterey County, she retrieved a specimen of this previously unrecorded plant and named this species after J. B. Hickman, her guide on that collecting trip. Eastwood's commitment to her work was demonstrated in the aftermath of the 1906 San Francisco earthquake. She rushed to the heavily damaged California Academy of Sciences building on Market Street, and climbed metal railings of collapsed staircases to reach the herbarium on the sixth floor, while the building was burning. She succeeded in saving nearly 1500 specimens, including the entire type specimen collection, before the remainder of the largest botanical collection in the western United States was consumed in the resulting fire.

Conservation status

In the year 1973 the state of California recognized Hickman's potentilla as an endangered species. In the early to mid 1990s a series of steps occurred that led to federal classification as an endangered species. Certain land development proposals came before the city of Monterey related to pine forest habitat area. In preparing an Environmental Impact Report, information on occurrences of Hickman’s potentilla was published. Subsequently in 1995 the U.S. Environmental Protection Agency (EPA) acted on this new information regarding a species that some thought extinct, and promulgated a notice of intent to classify the species as endangered.

In 1998 the United States Congress officially classified Hickman's potentilla as endangered. After the EPA nomination process, further colonies in San Mateo and Sonoma Counties became defined. This chain of events illustrates the role of the Environmental Impact Statement in elucidating scientific information germane to the understanding of an entire species, beyond the intended role of analyzing effects on the physical environment of a specific project.

P. Hickmanii continues to be pressured by urban development, especially on the Monterey Peninsula with chief elements of golf courses and housing to support the expanding human population. These pressures are partially mitigated by species protection and recovery plans, the latter of which is recognized by the county, local cities, Association of Monterey Bay Area Governments and the State of California. The federal Recovery Plan (internationally called Biodiversity Action Plan) is general in nature, calling for more natural history study, population surveys, generalized protection and a vague reference to new plantings. Ironically one of the best efforts to enhance the species may come from a program that is seemingly unaware of the species. The Fitzgerald Marine Reserve Master Plan calls for natural vegetative enhancement of Vicente Creek (exact location of the 1933 colony), including removal of fill and debris from the creek and extirpation of invasive plants. A chief rationale for this plan is protection of the California red-legged frog, also an endangered species.

As a further measure of protection, Monterey County, California has explicitly included Hickman's potentilla as a species to be protected via its Local Coastal Program pursuant to state of California requirements. While the species is listed as federally and state endangered, The California Native Plant Society has set the further designation of "seriously endangered". This appellation is provided to any plant that has fewer than six occurrences, exists on less than 2000 acres (8 km²) of land area or has fewer than 1000 known organisms. Hickman's potentilla satisfies the first criterion.

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