Endemic to the island of Kauai. This species is now known from only 2 locations, with fewer than 30 plants known to be extant. The major threats to this species are deer, pigs and alien plant species.
Threats to D. rhytidosperma include predation and habitat degradation by mule or black-tailed deer, feral pigs, and goats, and herbivory by rats and introduced slugs. Fire and competition with the alien plants such as Lantana camara (lantana), Passiflora
Number of Populations: 2 (USFWS 2001; K.R. Wood pers. comm.)
Number of Plants: 15 (USFWS 2001; K.R. Wood pers. comm.)
Seeds of D. rhytidosperma have been tested by the Center for Conservation Research (CCRT), the National Seed Storage Laboratory (NSSL), and the National Tropical Botanical Garden (NTBG), finding that they are orthodox, and can tolerate freezing and drying. The laboratory germination time was three weeks to six months (Yoshinaga 2002).
Plants and seedling of D. rhytidosperma have been collected by NTBG. It has also been successfully been propagated by tissue culture (USFWS 1995).
NTBG currently has ex situ holdings of numerous seeds in its seed bank, plants growing in the nursery, and seven plants growing in the botanical garden, which represent the single population. Extensive and reproducing populations are maintained in a semi-natural state at Limahuli Garden and Preserve (NTBG).
1. Survey historic range for surviving populations.
2. Maintain adequate genetic stock of D. rhytidosperma.
3. Conduct pollination biology and seed dispersal studies.
4. Map genetic diversity in the surviving populations of D. rhytidosperma, and identify conservation management units.
5. Test the influence of weeding and fencing on populations of D. rhytidosperma.
Recommendations derived from M.H. Chapin, M. Maunder, and USFWS (1995).
1. Establish secure ex situ stocks with full founder representation.
2. Develop proper horticultural protocols and pest management for D. rhytidosperma.
3. Survey ex situ holdings and conduct molecular fingerprinting.
Recommendations derived from M.H. Chapin and M. Maunder.
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