16-168

2 16.28 Taxon Summary: Viola chamissoniana subsp. chamissoniana

4 Photographer: Hawaii Natural Heritage Program

6 Scientific name: Viola chamissoniana Ging. subsp. chamissoniana Common name: Olopu, pamakani 8 Family: (Violet family) Federal status: Listed endangered 10 Description and biology: Viola chamissoniana subsp. chamissoniana is a woody shrub. This is 12 unusual in the genus Viola, as most non-Hawaiian species are small herbs. The taxon is basal- branching with branches measuring 20-60 cm (8-23 in) long. Some populations, especially the 14 ones on steep cliffs, have with lax, reclining or drooping branches. Other populations consist of plants with erect branches forming upright shrubs. At the end of each stem is a cluster 16 of roughly triangular leaves measuring about 2-4 cm (0.8-1.6 in) long. The taxon's flowers are large, white, and held above the leaves. Due to the conspicuousness of the flowers, flowering 18 plants are easily recognized from a distance. The seeds are borne in capsules that open as they dry. The seeds are egg-shaped, dark brown to almost black, and measure about 2 mm (0.1 in) 20 long.

22 Little is known about the taxon's breeding system. Its pollinators are as yet unrecorded. However, its large white fragrant flowers held above its leaves suggest it is moth pollinated. 24 Dispersal agents for this taxon are unknown. The longevity of individuals of the taxon is also unknown, but since the taxon is a small, woody , its longevity is presumed to be less than 10 26 years, and it is therefore a short-lived taxon for the purposes of the Implementation Plan.

28 Known distribution: Viola chamissoniana subsp. chamissoniana is known only from the Waianae Mountains. It has been recorded throughout the mountain range on both the windward 30 and leeward sides, and it has been found from 700-1,000 m (2,300-3,040 ft).

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32 Population trends: This taxon's population trends have not been well documented since all of the known populations were discovered only within the last two decades. However, since many 34 members of this taxon grow on the steep cliffs inaccessible to feral ungulates, it is likely that the taxon has not declined in numbers as steeply as most of the Makua target taxa that are not cliff 36 dwelling. It is also possible that the taxon was originally more common off the cliffs than it is nowadays, and has been able to survive only on the steeper cliffs inaccessible to feral ungulates. 38 Current status: There are six known population units of V. chamissoniana subsp. 40 chamissoniana, totaling almost 400 individuals. About 250 of these are within the Makua action area. The taxon's current population units are listed in Table 16.82 and their sites are plotted on 42 Map 16.41. All of the sites are proposed for management for stability. The sites are characterized in Table 16.83 and threats to the plants at these sites are identified in Table 16.84. 44 Habitat: Viola chamissoniana subsp. chamissoniana occurs in mesic habitats. At the majority 46 of the taxon's sites the plants grow on cliffs and cliff ledges that are usually north facing. Typically, few plants at these sites are reachable without the aid of ropes. These cliffs are 48 sparsely to moderately vegetated with native shrubs, grasses, and sedges. The steep north-facing cliffs in the Waianaes are among the mountain range’s most native and undisturbed of its mesic 50 habitats. Although the taxon is usually found growing on cliffs, there are sites where the plants are growing on gentle slopes in native shrubland. 52 Taxonomic background: There are seven species of Viola native to Hawaii; all are Hawaiian 54 endemics. Viola chamissoniana consists of two subspecies other than subsp. chamissoniana: subsp. tracheliifolia, which is endemic to , Oahu, , and ; and subsp. robusta, 56 which is endemic to Molokai. These two subspecies are not considered rare. Subspecies chamissoniana differs from the two subspecies primarily in its large white flowers held above its 58 leaves, whereas the other subspecies have relatively inconspicuous flowers borne amongst their leaves. 60 Outplanting considerations: The only other native Viola occurring in the Waianae Mountains 62 is the common V. chamissoniana subsp. tracheliifolia, which like subsp. chamissoniana, occurs throughout the mountain range. Subspecies tracheliifolia is generally found growing in the 64 forest understory, while subsp. chamissoniana is most often growing in open, exposed habitats. Several sites are known where the two subspecies grow side by side. Hybridization between the 66 two has not been reported in the wild, and the potential for it to occur is not known. Since subsp. chamissoniana occurs naturally in close proximity to the non-endangered subsp. tracheliifolia, 68 hybridization concerns are minimal. In any case, at any site with appropriate habitat for subsp. chamissoniana, it may be impossible to avoid planting adjacent to subsp. tracheliifolia. 70 Threats: Invasive alien plants gravely threaten V. chamissoniana subsp. chamissoniana by 72 altering the taxon's habitat and competing with it for moisture, nutrients, and growing space. Feral goats and pigs also threaten it, for although many individuals of the target taxon grow on 74 steep cliffs where they cannot be reached by the ungulates; many others are within their reach and are thus susceptible to predation. Furthermore, the animals degrade the plants’ habitat by 76 hastening the spread of invasive weeds. They also disturb the substrate above the cliffs, thereby

Final DACA83-96-D-0007/0055 Implementation Plan for Makua Military Reservation, Island of Oahu Chapter 16.28 Taxon Summary: Viola chamissoniana subsp. chamissoniana 16-170

increasing the size and frequency of landslides and rock falls on the cliff faces. These 78 disturbances directly affect even the plants inaccessible to the ungulates.

80 Table 16.82 Current Population Units of Viola chamissoniana subsp. 82 chamissoniana. The numbers of individuals include mature and immature plants, and do not include seedlings. Population units proposed for management are shaded. Island Population Unit Name Total No Management Number of Management Proposed Individuals Proposal Oahu: Halona 3 0 3 Kamaileunu 38 0 38 Makaha 50 0 50 Ohikilolo 250 0 250 Puu Hapapa 13 0 13 Puu Kumakalii 20 0 20 84

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Table 16.83 Site Characteristics for Population Units of Viola chamissoniana 86 subsp. chamissoniana Proposed for Management for Stability.

Population Unit: Site Characteristics: Habitat Quality Terrain Accessibility Existing Fence

Kamaileunu Medium- Low to Vertical Low None High-Medium Makaha Medium-Low to Vertical Low None High-Medium Ohikilolo Medium-Low to High Steep to Vertical Low to Medium None, Large

Puu Hapapa Medium- Low Steep to Vertical Low to Medium None

Puu Kumakalii Medium- Low Moderate High None

88 Table 16.84 Threats to Population Units of Viola chamissoniana subsp. 90 chamissoniana Proposed for Management for Stability.

Population Threats: Unit: Pigs Goats Weeds Rats Black Slugs Other Fire Fire Erosion Human Twig and Arthro- Ignition Fuels Distur- Borer Snails pods bance Kamaileunu Low Low to High Unknown Unknown Unknown Unknown Very Medium Low Low High A A A A high Makaha Low Low to High Unknown Unknown Unknown Unknown Very Medium Low Low High A A A A high Ohikilolo Low Low to Medium Unknown Unknown Unknown Unknown Very Medium Low Low to High A A A A high Medium Puu Hapapa N/A Medium Medium Unknown Unknown Unknown Unknown Medium Medium Low Medium A A A A Puu Kumakalii Medium N/A Medium Unknown Unknown Unknown Unknown High Medium Low Medium A A A A 92

94

96

98

100

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102

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