16-133

16.22 Taxon Summary: princeps var. princeps

2 Photographer: J. Obata 4 Scientific name: Plantago princeps Cham. & Schlechtend. var. princeps 6 Hawaiian name: Ale Family: (Plantain family) 8 Federal status: Listed endangered

10 Description and biology: Plantago princeps var. princeps is a woody , which is unusual for the genus. Most continental species in this genus are small herbs. The is either single 12 stemmed or sparingly branched at the base, and attains a height of at least 1 m (3.3 ft) tall. The leaves are arranged in a cluster at the tip of each branch, are strap-shaped, and measure up to 20 14 cm (7.8 in) long. Each stem tip usually bears several erect, axillary , each of which consists of a single stem bearing densely arranged flowers on its upper portion. The 16 flowers and capsules are small and inconspicuous. The capsules each bear 3-4 black seeds measuring 1.5-2.1 mm (0.06-0.08 in) long. 18 Flowering and fruiting specimens have been collected throughout the year. The surface of the 20 seed is covered by a mucilaginous membrane (Wagner et al. 1990), which is theorized to cause the seeds to stick to animals (Carlquist 1974). With the complete absence of ground mammals in 22 prior to the arrival of the Polynesians, birds, including the many now extinct flightless species, would have been the primary dispersal agents of Hawaiian Plantagos. Little is known 24 about the target taxon’s breeding system and pollination. The longevity of individuals of this taxon is unknown, but since the plant is a small shrub, its longevity is presumed to be less than 26 10 years, and it is therefore a short-lived taxon for the purposes of the Implementation Plan.

28 Known distribution: Plantago princeps var. princeps has been recorded from three general areas on the island of Oahu. Most of the currently known are scattered at locations 30 throughout the Waianae Mountains, on both the leeward and windward sides of the mountain

Final DACA83-96-D-0007/0055 Implementation Plan for Makua Military Reservation, Island of Oahu Chapter 16.22 Taxon Summary: Plantago princeps var. princeps 16-134

range. There are also historical records of it from the southeastern Koolau Mountains in the 32 valleys of Kalihi, Nuuanu, and Manoa. It has not been observed in that region for over half a century. The taxon was discovered for the first time in the central Koolau Mountains in 2001, 34 when plants were found at Waiawa. These plants are located just a short distance to the lee of the Koolau summit ridge. Recorded elevations for the plant range from 480-792 m (1,580-2,600 36 ft).

38 Population trends: When P. princeps var. princeps was rediscovered in 1987 in the Waianae Range, it had not been seen in over half a century in the Koolaus, and not since the 1800’s in the 40 Waianaes. Since all currently known colonies of the taxon were discovered relatively recently, the taxon's population trends are not well documented. The colony of plants discovered in 1987 42 in the North Branch of North Palawai Gulch is the only colony for which a trend has been observed. When found in 1987, the colony contained approximately 20 plants, but only five 44 have been seen in the last five years. In this case, the taxon's rapid decline can be attributed to competition from daisy fleabane (Erigeron karvinskianus), a highly invasive alien plant. 46 Current status: The known population units of P. princeps var. princeps in the Waianae 48 Mountains total approximately 200 plants. About 26 individuals are found within the Makua action area. The Waiawa population unit in the Koolau Mountains consists of two mature plants 50 and about 40 immature ones. The species' current population units are listed in Table 16.64 and their sites are plotted on Maps 16.33 and 16.34. All are proposed for management for stability. 52 Their sites are characterized in Table 16.65 and threats to the plants at these sites are identified in Table 16.66. 54 Habitat: Plantago princeps var. princeps occurs in two extremely different types of habitat. In 56 the Waianae Mountains the plants are found in the mesic vegetation on cliff faces, cliff ledges, and at the bases of cliffs. The majority of these plants are accessible only with the help of ropes. 58 Their cliff habitat is vegetated with native grasses, sedges, herbs, and . The historic southeastern Koolau Range plants also grew in mesic cliff habitats. In contrast, the Waiawa 60 plants are situated in a rainforest area close to the Koolau summit ridge, which receives more precipitation than anywhere else on the island. The plants were observed to be growing on a 62 streamside embankment (Perlman pers. comm. 2000).

64 Taxonomic background: Plantago princeps is endemic to the Hawaiian Islands. The species is divided into four varieties: var. anomala of ; var. laxiflora of , , and Hawaii; 66 var. longibracteata of Kauai and the Koolau Mountains of Oahu; and var. princeps of both mountain ranges on Oahu. All of the varieties except var. longibracteata are sizable woody 68 shrubs. In contrast, var. longibracteata is a small herb.

70 When the Waianae Range plants were rediscovered in 1987, the specimens collected were identified as var. anomala. Only the southeastern Koolau Range plants were considered to 72 represent var. princeps (Wagner et al. 1990). The Waianae Range plants were subsequently reclassified as var. princeps (Wagner et al. 1999). 74 Outplanting considerations: Plantago princeps var. princeps is the only native Plantago in the 76 Waianae Mountains. The situation is more complex in the Koolau Mountains, where in addition

Final DACA83-96-D-0007/0055 Implementation Plan for Makua Military Reservation, Island of Oahu Chapter 16.22 Taxon Summary: Plantago princeps var. princeps 16-135

to var. princeps, there is another variety of P. princeps recorded, namely var. longibracteata. 78 This variety is known from historical specimens collected on the windward side of the Koolaus in the Kaluanui area between Punaluu Valley and Hauula. It has been recorded on wet cliffs and 80 alongside waterfalls. Additionally, there is a second native species in the Koolaus, P. pachyphylla, which is common in the Koolau summit areas. On Kauai, P. princeps var. 82 longibracteata and P. pachyphylla form a hybrid population at the Waialeale summit (Bruegmann pers. comm. 2000). It is not yet known whether the ranges of P. pachyphylla or P. 84 princeps var. longibracteata overlap that of P. princeps var. princeps in the Koolau rainforests, and whether any hybridization occurs or could potentially occur. No outplantings are currently 86 proposed in the Koolaus, but if they are deemed necessary in the future, further study should be conducted on the distribution of Plantago taxa in the Koolau Range, and their potential for 88 hybridization.

90 Given the extreme differences between the habitats of the Waianae Range and Waiawa plants, it would not be prudent to mix the two stocks at a single outplanting site. 92 Threats: The primary threats to P. princeps var. princeps of the Waianae Mountains include 94 feral pigs and goats. Only a few goats are present in the Koolau Mountains, and none are in the rainforests of the mountain range. Pigs, however, are common in parts of the Koolaus and they 96 likely threaten the Waiawa population unit. Various alien plant species threaten P. princeps var. princeps by altering its habitat and competing with it for sunlight, moisture, nutrients, and 98 growing space. Also, the spread of highly flammable alien grasses increases the incidence and destructiveness of wildfires. The alien weed threats are worse in the mesic Waianae sites than in 100 the wet Waiawa site in the Koolaus.

102 Table 16.64 Current Population Units of Plantago princeps var. princeps. The 104 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 Proposed Oahu: Ekahanui 23 0 23 Halona 50 – 100 0 50 – 100 North Branch of North Palawai 7 0 7 North Mohiakea 30 0 30 Ohikilolo 14 0 14 Pahole 12 0 12 South Branch of North Palawai 25 0 25 Waiawa (Koolaus) 42 0 42 106

108

110

Final DACA83-96-D-0007/0055 Implementation Plan for Makua Military Reservation, Island of Oahu Chapter 16.22 Taxon Summary: Plantago princeps var. princeps 16-136

112 Table 16.65 Site Characteristics for Population Units of Plantago princeps var. princeps Proposed for Management for Stability. 114 Population Unit: Site Characteristics: Habitat Quality Terrain Accessibility Existing Fence

Ekahanui High- Medium Moderate to Vertical Low to High None

Halona High- Medium Vertical Low None

North Mohiakea High Vertical Low None

Ohikilolo High-Medium Steep to Vertical Low to Medium Large

South Branch of North Medium-Low Steep Medium None Palawai Waiawa (Koolaus) High Steep Low None

116 Table 16.66 Threats to Population Units of Plantago princeps var. princeps Proposed for Management for Stability. 118 Population Threats: Unit: Pigs Goats Weeds Rats Black Slugs Other Fire Fire Erosion Human Twig and Arthro- Ignition Fuels Distur- Borer Snails pods bance Ekahanui Low to Low High Unknown Unknown Unknown Unknown High Medium Low Medium High A A A A Halona Low to Low High Unknown Unknown Unknown Unknown Very Medium Low Low High A A A A high North Mohiakea Low N/A Medium Unknown Unknown Unknown Unknown Very Medium Low Low A A A A high Ohikilolo Low Low Medium Unknown Unknown Unknown Unknown Very Medium Low Low A A A A high South Branch of High N/A High Unknown Unknown Unknown Unknown High Medium Low Medium North Palawai A A A A Waiawa High N/A Medium Unknown Unknown Unknown Unknown Low Low Low Low (Koolaus) A A A A

Final DACA83-96-D-0007/0055 Implementation Plan for Makua Military Reservation, Island of Oahu Chapter 16.22 Taxon Summary: Plantago princeps var. princeps 16-137

120

Final DACA83-96-D-0007/0055 Implementation Plan for Makua Military Reservation, Island of Oahu Chapter 16.22 Taxon Summary: Plantago princeps var. princeps 16-138

122

Final DACA83-96-D-0007/0055 Implementation Plan for Makua Military Reservation, Island of Oahu