The following Participating Institutions are custodians for this species in the CPC National Collection:
Santa Barbara Botanic Garden
The conservation of Helianthemum greenei is fully sponsored.
Dieter Wilken, Ph.D. contributed to this Plant Profile.
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.
Distribution & Occurrence
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.
|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.|
Conservation, Ecology & Research
Seed germination is enhanced by scarification and/or heat (Wilken pers. obs.).
Highest densities of plants were found in open sites among completely burned shrubs after a fire on Santa Cruz Island (Wilken pers. obs.).
Plants can be found on a diversity of substrates, ranging from fine-grained shales to rocky volcanic soils, and occasionally alluvial deposits in ephemeral stream channels.
Loss of small populations as a result of feral pig activities.
Competition from noxious weeds.
Erosion at sites near established roads.
Seed biology is being studied by Carol Baskin at the University of Kentucky.
Studies of ecological factors that influence establishment and survival, including competitive effects of native vegetation and potential mycorrhizal relationships.