Phyllostegia parviflora

No Common Name

Description

Phyllostegia parviflora is a perennial herb of the mint family (Lamiaceae). The egg-shaped to broadly egg-shaped, wrinkled leaves are usually 7.5-13 in (19-33 cm) long and 3-6 in (7.6-15.2 cm) wide. The leaf stalks are typically 2.4-5.3 in (6-13.5 cm) long. Usually six flowers are arranged along a flowering stalk. The corolla is white, sometimes tinged with purple, and about 0.4-0.5 in (1-1.3 cm) long. The upper corolla lip is about 0.1 in (2.5 mm) long, while the lower lip is about 0.2-0.4 in (5-10 mm) long. The fruits are nutlets.

The species is distinguished from others of the genus by the leaf shape and length of the leaf stalk and lower corolla lip. P. p. var. glabriuscula has fewer glandular hairs in the inflorescence, less pubescent leaves, and usually unbranched inflorescences, as compared to P. p. var. parviflora. The newly discovered variety of P. parviflora has shorter leaf stalks, spreading hairs on the leaf stalks, and fewer gland-tipped hairs in the inflorescence.

P. parviflora was first described as Prasium parviflorum based on a specimen collected on Oahu in 1888. The species was later transferred to Phyllostegia, the name accepted in the current treatment of Hawaiian members of the genus. Two varieties are currently recognized—var. parviflora and var. glabriuscula, described in 1862. There is also a newly discovered variety that has not yet been formally named. These recent collections of P. parviflora from the Waianae Mountains differ from the other varieties by several characteristics; they represent a new variety previously considered to be P. mollis var. lydgatei. Current taxonomy considers the published names P. leptostachys, P. parviflora var. canescens, P. parviflora var. gaudichaudii, and P. parviflora var. major to be synonymous with P. parviflora var. parviflora.

Habitat

P. parviflora is typically found on moderate to steep slopes in diverse wet forest at elevations of 1,640-2,700 ft (500-820 m). Native species associated with P. parviflora include 'ohi'a, Broussaisia arguta (kanawao), Mysine sp. (kolea), Pipturus albidus (mamaki), and Cyrtandra sp. (haiwale).

Distribution

P. parviflora was known historically from the Hawaiian islands of Oahu, Hawaii, and Maui. This species is now known from only two populations on Oahu. P. parviflora var. glabriuscula was known only from the island of Hawaii on private land and has not been observed since the 1800s. P. parviflora var. parviflora had historical occurrences on Oahu and Maui, but it is now known on Oahu from just four plants in North Kaukonahua Stream in the Koolau Mountains on state land leased by the U. S. Department of Defense for the Kawailoa Training Area. The new variety of P. parviflora is known from only 19 plants in North Palawai Gulch within the Nature Conservancy's Honouliuli Preserve.

Threats

The major threats to P. parviflora are habitat degradation and destruction by feral pigs, competition with several alien plants, and a risk of extinction from naturally occurring events and reduced reproductive vigor due to the small number of remaining individuals and populations.

The two remaining populations of P. parviflora on Oahu are threatened by pigs.

Collecting for scientific or horticultural purposes and visits by individuals avid to see rare plants are potential threats to P. parviflora.

Christmas berry, now a major component of the mesic forests of the Waianae and Koolau Mountains of Oahu, threatens one of two known populations of P. parviflora there. In the Waianae Mountains, Koster's curse and thimbleberry pose serious threats to the largest population of P. parviflora. The newly discovered and still undescribed variety of P. parviflora is potentially threatened by fire and cattle.

Conservation and Recovery

Several miles of pig-proof fencing was constructed in Palawai Gulch in 1997; the fencing enclosed approximately 90 acres (36 hectares) of rare plant habitat, including the P. parviflora population.

P. parviflora has been successfully propagated at Lyon Arboretum.

Contact

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

Reference

U. S. Fish and Wildlife Service. 10 October 1996. "Determination of Endangered or Threatened Status for 14 Plant Taxa from the Hawaiian Islands." Federal Register 61 (198): 53108-53124.