Endemic to the northwestern coast of the island of Kauai. This species is restricted to a narrow broken band of rocky coastline not far above sea level. Currently, fewer than 200 plants are known at 4 locations. Goats are the major cause of decline in this species, due to predation and habitat degradation. The species is now almost entirely restricted to sites inaccessible to goats. Alien weeds also represent a threat to this species. Other potential threats are landslides and fire.
Threats to H. st.-johnii include:
herbivory and habitat degradation by feral goats
competition from alien plant species, especially Pluchea carolinensis (sour bush)
trampling and grazing by cattle
a risk of extinction due to na
Number of Populations: 4 (USFWS 2001)
Number of Plants: 200 (USFWS 2001)
The seeds of H. st.-johnii have been tested by the National Seed Storage Laboratory (NSSL), finding that they are orthodox and can tolerate freezing and drying. The laboratory germination time was 6 months (Yoshinaga 2002).
The National Tropical Botanical Garden (NTBG) currently has ex situ collections of numerous seeds, representing all four populations. There are 18 individuals representing one population in the nursery, and five plants growing in the grounds of the botanical garden from an unknown locality.
1. Map genetic diversity in the surviving populations of H. st.-johnii.
2. Test the influence of weeding and fencing on populations of H. st.-johnii.
3. Conduct pollination biology and seed dispersal studies.
4. Establish protection and management for all extant populations.
Recommendations derived from M.H. Chapin, and M. Maunder.
1. Establish secure ex situ stocks with full founder representation.
2. Develop proper horticultural protocols and pest management for H. st.-johnii.
3. Survey ex situ holdings and conduct molecular fingerprinting.
Recommendations derived from M.H. Chapin and M. Maunder.
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