Island Bedstraw

Galium buxifolium

Description

Galium buxifolium (island bedstraw) was described in 1886 based on specimens collected on Santa Cruz Island. The taxon was described as a variety of G. catalinense in 1958. In 1960 it was suggested that the taxon was sub-specifically distinct from G. catalinense. In 1973, the taxon was recognized as a separate species based on nutlet hair differences between it and G. catalinense.

G. buxifolium is a small, stout woody shrub in the bedstraw (Rubiaceae) family. The plant grows to 4 ft (1.2 m) in height, and has swollen nodes bearing numerous leafy branches. The leaves are larger than those of most other Galium taxa, and have conspicuous lateral veins with stout hairs on the lower surface. The relatively broad leaves and the tiny upward-curved hairs that cover the fruits are unique characteristics that distinguish it from the six other species of Galium that occur on the islands.

Habitat

G. buxifolium occurs on "bluffs and rocky slopes" in coastal sage scrub and island pine forest.

Distribution

A putative collection of G. buxifolium made from the "Torrey Pine grove, Santa Rosa Island," in 1941 was a misidentified collection of G. nuttallii. Therefore no collections of this taxon are known from Santa Rosa Island. G. buxifolium is currently known from Santa Cruz and San Miguel Islands where it occurs on north-facing sea cliffs. Eight populations occur on the Nature Conservancy (TNC) lands on Santa Cruz Island. A 1980 study noted that two of these populations had less than 50 individuals each, while the remaining populations had less than six individuals each. No recent status information is available for the Santa Cruz Island populations. Two populations were located on San Miguel Island in 1993, one with about 200 individuals, and the other having less than 10 plants. Five other historical collections have been made from the island, but no plants have been seen at these other localities for almost 30 years.

Threats

G. buxifolium is threatened by habitat alteration caused by soil loss and herbivory from feral pig rooting and sheep grazing.

G. buxifolium is threatened on Santa Cruz Island where trampling and pig rooting along the sea cliffs increases the likelihood of slope failure.

Conservation and Recovery

The island bedstraw occurs only as small populations on Santa Cruz and San Miguel Islands. The western 90% of Santa Cruz Island is privately owned and managed by TNC, a private conservation organization, and the other 10% is federal land managed by the National Parks Service. San Miguel Island is under the jurisdiction of the U.S. Department of the Navy, but the National Parks Service has operational jurisdiction. Both of these islands are being managed as natural areas. However, the rare plant is still threatened by competition and habitat changes caused by invasive alien plants, by introduced mammalian herbivores, and other factors.

The survival of this endangered plant requires strict protection from the feeding of mammals. This could be done by securely fencing known plants, or by eradicating the mammals from the critical habitat. Competing alien plants must also be reduced in abundance. The populations of the island bedstraw should be monitored, and research undertaken into its basic biology and ecological requirements. It should be propagated in captivity, to provide stock for out-planting to supplement the small wild populations, and to establish new ones in suitable habitat.

Contact

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

Reference

U. S. Fish and Wildlife Service. 31 July 1997. "Final Rule for 13 Plant Taxa from the Northern Channel Islands, California. Federal Register 62 (147): 40954-40974.