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Plant Profile

Island Rushrose (Helianthemum greenei)

Mature plants may produce up to 100 flowers on stalks that grow up to 0.5 m tall. Photo Credit: Dieter Wilken

Global Rank: G3 - Vulnerable
Legal Status: Federally Threatened
Family: Cistaceae
State: CA
Nature Serve ID: 130577
Lifeform: Subshrub, Shrub, Forb/herb
Date Inducted in National Collection: 05/01/1999

Description:

Flowers have 5 bright yellow petals and are about 2 cm in diameter. One-year-old plants with 1-5 flowers may be only 10-15 cm tall. However, mature plants may reach 0.5 m in height, producing up to 100 flowers on multiple branches, and may live for up to 10 years. The minute, black, globose seeds, less than 0.5 mm in diameter, have exceedingly thick coats and show low rates of germination unless abraded and/or heated. Most occurrences are each composed of 1 to 7 widely scattered plants. However, a few large populations with high densities have been found in burned chaparral, with most plants persisting for about 4-5 years.

Where is Island Rushrose (Helianthemum greenei) located in the wild?

Habitat:

Open sites on rocky to gravelly soils of bluffs, slopes, and ridges, often in chaparral or mixed oak-pine woodland. Common associates include Pinus muricata and species of Arctostaphylos, Ceanothus, Eriogonum, and Quercus.

Distribution:

Santa Catalina, Santa Cruz, and Santa Rosa islands.

States & Provinces:

Island Rushrose can be found in California

Which CPC Partners conserve Island Rushrose (Helianthemum greenei)?

Santa Barbara Botanic Garden

Not Sponsored

Conservation Actions

Assigned 06/09/17

CPC's Plant Sponsorship Program provides long term stewardship of rare plants in our National Collection. We are so grateful for all our donors who have made the Plant Sponsorship Program so successful. We are in the process of acknowledging all our wonderful plant sponsorship donors on our website. This is a work in progress and will be updated regularly.

Conservation Actions

09/15/2020

Demography is being studied on Santa Cruz island by the Santa Barbara Botanic Garden. Populations on Santa Catalina and Santa Rosa islands are being monitored by the Catalina Island Conservancy and the National Park Service, respectively.

09/01/2020

Based on an September 2020 extract of the California Plant Rescue Database, Santa Barbara Botanic Garden holds 38 accessions of Crocanthemum greenei in orthodox seed collection. There are as many as 25899 seeds of this species in their collection - although some may have been used for curation testing or sent to back up.

09/01/2020

Based on an September 2020 extract of the California Plant Rescue Database, National Laboratory for Genetic Resource Preservation (USDA-ARS) holds 1 accessions of Crocanthemum greenei in orthodox seed collection. There are as many as 1500 seeds of this species in their collection - although some may have been used for curation testing or sent to back up.

08/05/2020

Based on an August 2020 extract of the California Plant Rescue Database, Santa Barbara Botanic Garden has collected 39 seed accessions of Crocanthemum greenei from 16 plant occurrences listed in the California Natural Diversity Database. These collections together emcompass 288 maternal plants

Nature Serve Biotics

05/02/2017

Historically known from 3 of the northern Channel Islands and Santa Catalina Island off the coast of southern California. Now probably extant only on Santa Cruz and Santa Catalina islands. There are 15 recently verified occurrences, most with very small numbers of individuals. Only 4 populations - all in areas areas that burned in 1994 - have more than 500 individuals; most of the others have < 10 individuals. Threats include alteration of the natural fire regime and competition with other shrubs under altered habitat conditions. Habitat for the plant plant on Santa Catalina - where only 3 individuals are known - is being grazed by non-native goats, deer, and bison and is being rooted by feral pigs. And all of the northern Channel Islands have suffered profound loss and degradation of their soils and changes in their plant communities due to the large numbers of non-native mammals introduced to the islands starting in the early 1800's.

Dieter Wilken, Ph.D.

01/01/2010

As listed in the recovery plan for thirteen plants from the northern channel islands (USFWS 2000): Loss of small populations as a result of feral pig activities. Competition from noxious weeds. Erosion at sites near established roads.

Dieter Wilken, Ph.D.

01/01/2010

At least 14 occurrences have been documented, including one each on Santa Catalina and Santa Rosa islands respectively. The remaining 12 are known from widely scattered localities on Santa Cruz Island. Most occurrences are composed of less than 10 plants each. However, one area on Santa Cruz Island, which was burned in 1994, supported several 1000 individuals for 4-5 years, followed by a decline to a few hundred individuals in 2000.

Dieter Wilken, Ph.D.

01/01/2010

Dieter Wilken, Ph.D.

01/01/2010

The population on Santa Catalina Island is managed by the Catalina Island Conservancy and is protected from disturbance by feral goats and pigs. The population on Santa Rosa Island is managed by the National Park Service and is protected from grazing by feral deer and elk. Populations on Santa Cruz Island occur on lands owned and managed partly by The Nature Conservancy and partly by the National Park Service. The Nature Conservancy and the National Park Service are working collaboratively to develop a plan for weed control and removal of feral pigs, but no short-term measures have been taken to protect vulnerable populations.

Dieter Wilken, Ph.D.

01/01/2010

Genetic analyses within and among populations, including the natural seed bank. Studies of ecological factors that influence establishment and survival, including competitive effects of native vegetation and potential mycorrhizal relationships.

Dieter Wilken, Ph.D.

01/01/2010

Seed collections representing the entire geographic distribution.