Phyllostegia warshaueri

No Common Name

Description

Phyllostegia warshaueri, a member of the mint family, is a sprawling or a climbing vine with end branches that turn up. Upward-pointing, fine, short hairs cover the square stems, which are about 3.3-10 ft (1-3 m) long. The opposite, nearly hairless, toothed leaves are 3.7-7.9 in (9.4-20.1 cm) long and 0.8-2.6 in (2-6.6 cm) wide. Six to 14 flowers are borne in an unbranched inflorescence 7.9 in (20.1 cm) in length with a main stalk 1.0-1.6 in (2.5-4.1 cm) long and conspicuous leaflike bracts.

The green, hairless, cone-shaped calyx is 0.2-0.3 in (5.1-7.6 mm) long and has triangular lobes. The sparsely hairy corolla is white with a dark rose upper lip; it has a tube about 0.2 in (5.1 mm) long and a lower lip 0.5-0.6 in (1.3-1.5 cm) long. Fruits are divided into four nutlets about 0.2-0.3 in (5.1-7.6 mm) in length. This species is distinguished from others in this genus by its long main stalk to the flower.

The designation of the species P. warshaueri was a complicated process. P. ambigua var. longipes —first collected in the Kohala Mountains of Hawaii by J.M. Lydgate—was named in 1888. E. E. Sherff did not consider P. ambigua different from P. brevidens, so he created the combination P. brevidens var. longipes. Based on newly collected material, this variety was considered sufficiently different to warrant designation as the species P. warshaueri.

Habitat

This species grows in 'ohi'a and hapu'u montane wet forest (in which koa or olapa may co-dominate) at elevations of 2,400-3,770 ft (731.5-1,149.1 m). Associated taxa include Sadleria sp. ('amau); hapu'us; Broussaisia arguta (kanawao); mamaki; Dubautia plantaginea (na'ena'e); 'oha wai; ho'i'o; Machaerina angustifolia ('uki'uki); Cyanea pilosa (haha); and other species of Cyanea.

Distribution

Historically, P. warshaueri was found only on the island of Hawaii, in the Hamakua region on the northern slopes of Mauna Kea and in the Kohala Mountains. The only known individuals occur in two populations near the Hamakua Ditch Trail in the Kohala Mountains, on privately owned land. The total number of individuals is five to ten.

Threats

The major threats to P. warshaueri are habitat destruction by pigs; competition from alien plant taxa like thimbleberry, strawberry guava, palmgrass, Juncus planifolius, and glorybush; ditch improvements and road clearing; and a risk of extinction from naturally occurring events and/or reduced reproductive vigor due to the small number of existing individuals in the one remaining population.

Conservation and Recovery

As of May 1998 Volcano Rare Plant Facility held 11 plants in their nursery; National Tropical Botanical Garden had one plant and 346 seeds; the Lyon Arboretum two plants. Efforts are under way to develop a biocontrol program for glorybush and strawberry guava.

Contacts

U. S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
Eastside Federal Complex
911 N. E. 11th Ave.
Portland, Oregon 97232-4181
(503) 231-6121
http://pacific.fws.gov/

Pacific Remote Islands Ecological Services Field Office
300 Ala Moana Blvd., Room 3-122
P. O. Box 50088
Honolulu, Hawaii 96850
Telephone: (808) 541-1201
Fax: (808) 541-1216

Reference

U. S. Fish and Wildlife Service. 1998. "Big Island II: Addendum to the Recovery Plan for the Big Island Plant Cluster." U.S. Fish and Wildlife Service, Portland, Oregon. 80 pp., plus appendices.