The following Participating Institutions are custodians for this species in the CPC National Collection:
The conservation of Marsilea villosa is fully sponsored.
David Orr contributed to this Plant Profile.
Marsilea villosa is a fern found only in the Hawaiian Islands, restricted to areas with irregular flooding regimes. Currently, it is known from 3 populations of O`ahu and 2 population on Moloka`i. Many of the historic populations on O`ahu were destroyed by drainage of ponding areas, habitat degradation, competition from alien plants, off road vehicles and development.
Marsilea villosa resembles a four-leaf clover, with four leaflets borne at the end of a leaf stalk. The plant occurs either in scattered clumps or as a dense interwoven mat, depending on the competition with other species for limited habitat resources. Marsilea villosa requires periodic flooding for spore release and fertilization, then a decrease in water levels for the young plants to establish, and finally dry soil for the plants to mature.
Distribution & Occurrence
Restricted to areas with irregular flooding regimes and low elevations. Grows in small shallow depressions in silty clay or sand common in dry areas of most islands where winter rains create seasonal pools (USFWS 1996).
Moloka`i- Kamaka`ipo and Moki`o
|O`ahu- Lualualei- 1 population
O`ahu- Makapu`u- 1 population
O`ahu- Koko Head- 1 population
Moloka`i- Kamaka`ipo-1 population
Moloka`i- Moki`o- 1 population
Approximately 4000 plants total
(USFWS 1996, 2001)
Conservation, Ecology & Research
Habitat degradation by off-road vehicles.
Small population size.
Trampling by humans and animals.
Browsing by feral animals.
(USFWS 1996, 2001)
Propagation-rhizomes and sporocarps.
Lualualei- removal of cattle and monitoring
Koko Head- barrier created around population. Removal of alien plant species. Monitoring.
Kamaka`ipo- Adjustment of condominium and golf course plans by private developers.
Decrease human and animal disturbance.
Control alien plant species.
Propagation- germplasm preservation, increase numbers of individuals.
Franklin, I.A. 1980. Evolutionary change in small populations. In: Soule, M.E. ; Wilcox, B.A., editors. Conservation biology: an evolutionary-ecological perspective. Sinauer Associates. Sunderland, Massachusetts. p 135-149.
Garnett, W. 1990. Plants in the National Collection of the Center for Plant Conservation growing at Waimea Arboretum Botanical Garden. Notes from Waimea Arboretum & Botanical Garden. 17, 2: 4-16.
Harrington, H.D. 1964. Manual of the plants of Colorado. Chicago, IL: The Swallow Press Inc. 666p.
USFWS. 1991. Listing Proposals. Endangered Species Technical Bulletin. 16, 3: 4-5.
USFWS. 1991. Proposed endangered status for a Hawaiian plant, Marsilea villosa ('ihi'ihi). Federal Register. 1991, 56: 6350-6353.
USFWS. 2000. Determinations of Whether Designation of Critical Habitat Is Prudent for 20 Plant Species and the Proposed Designations of Critical Habitat for 32 Plant Species From the Island of Molokai, HI. Federal Register. 65, 251: 83158-83216.
USFWS. 2002. Designations of Critical Habitat for Plant Species From the Island of Oahu, Hawaii. Federal Register. 67, 102: 37108-37156.
USFWS. 2002. Revised Determinations of Prudency and Proposed Designations of Critical Habitat for Plant Species From the Island of Molokai, Hawaii. Federal Register. 67, 66: 16492-16579.
Wester, L.W. 1994. Weed management and habitat protection of rare species: A case study of the Endemic Hawaiian Fern, Marsilea villosa. Biological Conservation. 68, 1: 1-9.