Soft Bird's-beak

Cordylanthus mollis ssp. mollis

Description

Charles Wright collected the type specimen of Cordylanthus mollis ssp. mollis in November 1855 on Mare Island in San Francisco Bay. Asa Gray published the original description 13 years later, using the name Cordylanthus mollis. This taxon was treated as Adenostegia mollis in 1891 and Chloropyron molle in 1907. Tsan-Iang Chuang and Larry Heckard treated Cordylanthus mollis and Cordylanthus hispidus as subspecies of Cordylanthus mollis in 1973, with Cordylanthus mollis ssp. mollis recognized as the autonym.

C. mollis ssp. mollis is an annual herb of the snapdragon family (Scrophulariaceae) that grows 10-16 in (25-40 cm) tall, is sparingly branched from the middle up, and flowers between July and September. This species is a hemiparasite that extracts water and nutrients by attaching enlarged root structures to the roots of other plants. The foliage is grayish-green, often tinged a deep red, and hairy. The oblong or lance-shaped leaves are 0.4-1 in (1-2.5 cm) long, the lower leaves entire and the upper with one to three pairs of leaf lobes. The inflorescence consists of spikes 2-6 in (5-15 cm) long. A floral bract with two to three pairs of lobes occurs immediately below each inconspicuous white or yellowish-white flower. The flowers have only two functional stamens. The narrow ovoid seed capsule is 0.2-0.4 in (1-2.5 cm) long and bears 20 to 30 dark brown seeds. C. mollis ssp. mollis is distinguished from C. maritimus ssp. palustris by its two functional stamens and by its bracts with two to three pairs of lateral lobes. (C. maritimus ssp. palustris has four functional stamens and a pair of short teeth on the floral bracts.) C. mollis ssp. mollis can be differentiated most consistently from the closely related C. mollis ssp. hispidus by spike length and seed size, then secondarily by branching patterns and hirsuteness.

Habitat

C. mollis ssp. mollis is found predominantly in the upper reaches of salt grass-pickleweed marshes at or near the limits of tidal action. It is associated with Virginia glasswort (Salicornia virginica ), Distichlis spicata, fleshy jaumea (Jaumea carnosa ), alkali heath (Frankenia salina ), and arrow-grass (Triglochin maritima ).

Distribution

There have been 21 reported locations of C. mollis ssp. mollis, two of which (Denverton and Berkeley) were erroneous. The Mare Island, Martinez, Burdell Station, Bentley Wharf, and Antioch Bridge populations have been extirpated by habitat loss or modification.

The type locality for this taxon at Mare Island was destroyed by development and is now a dredge disposal site. The occurrence near Martinez in Contra Costa and Solano Counties, last seen in 1981, was dredged, filled, and diked for a marina.

Five other sites surveyed in 1993 no longer had the plants, although some potential habitat still existed. Nine occurrences are presumed to still exist, and these are widely scattered throughout coastal salt or brackish tidal marshes fringing San Pablo and Suisun Bays in Contra Costa, Napa, and Solano Counties. The Point Pinole, Rush Ranch, and Joice Island Bridge sites have very limited habitat and cover less than 1 acre (0.4 hectare) each. The population at Fagan Slough covers approximately 3 acres (1.2 hectares). The two largest populations are located at Hill Slough and at Concord Naval Weapons Station, each covering approximately 10 acres (4 hectares). The entire distribution of C. mollis ssp. mollis is currently restricted to about 31 acres (12 hectares) of occupied habitat. The total number of individuals reported among populations varies from one at the smallest site to 150,000 plants at the largest site. Most remaining sites have between 1,000 and 6,000 individuals, although the McAvoy site has only 23 plants. Individual populations fluctuate in size from year to year, as is typical of annual plants.

C. mollis ssp. mollis occurs primarily on private or non-federal land; the second-largest occurrence is found on Department of Defense (U.S. Navy) land.

The California Department of Water Resources (CDWR) conducted surveys for C. mollis ssp. mollis in the mid-1990s; these surveys extended even beyond the historical range of the species.

The CDWR surveyed potential habitat throughout Suisun Marsh, searched portions of the potential habitat along the Contra Costa shoreline, assisted with searches downstream of Suisun Bay in the Carquinez Strait and Napa marshes, and surveyed diked wetlands managed for waterfowl. No new populations of this taxon were found during these surveys.

Threats

Urbanization, industrial development, and agricultural land conversion have extirpated or potentially extirpated nearly 45% of known historical occurrences of C. mollis ssp. mollis, leaving only 31 acres (12 hectares) of occupied habitat to support the species. Indirect effects of urbanization leading to habitat fragmentation, projects that alter natural tidal regimes, increases in salinity of tidal marshes due to upstream withdrawals of freshwater, water pollution, mosquito abatement activities, insect predation, erosion, foot traffic, and extirpation due to genetic and demographic problems continue to threaten most remaining occurrences of C. mollis ssp. mollis.

Some of the projected highway construction in the San Francisco Bay Estuary will threaten C. mollis ssp. mollis by eliminating habitat into which existing populations of this plant could expand. The widening of California Highway 37 will harm wet-lands that occur along the Napa River and may adversely affect habitat for C. mollis ssp. mollis.

The proposed widening of Highway 12 near the Suisun Marsh would threaten this taxon through further habitat fragmentation and damage for increased runoff.

In addition to the threat posed by an excess of tidal marsh salinity, there is the potential threat toC. mollis ssp. mollis presented by decreased salinity within the Suisun Marsh. Reduced salt levels there may threaten this taxon by affecting its host plants.C. mollis ssp. mollis is a hemi-root parasite that completes its life cycle by parasitizing the roots of perennial halophytes. Salicornia virginica and Distichlis spicata are halophyte plant associates and likely hosts of C. mollis ssp. mollis, although specifics of the host relationship have yet to be determined. These two plant associates decreased in abundance in areas where C. mollis ssp. mollis occurred during the abnormally rainy years of 1995 and 1996, when excessive freshwater inflow diluted marsh salinity. This situation underscores the importance of maintaining the long-term natural variability of hydro-logic conditions in order to ensure the survival of host plants that C. mollis ssp. mollis may depend heavily on.

The health of one of the largest occurrences of this taxon is declining due to insect predation. Intense insect seed predation has been observed in the population at Joice Island and Hill Slough within Suisun Marsh in Solano County.

Erosion is a threat to C. mollis ssp. mollis located on the Point Pinole Regional Seashore. The main population of this taxon is immediately adjacent to a slough that is undergoing bank slumping. Individual plants are threatened by bank undercutting and the subsequent slippage of the marsh soil into the slough.

Foot traffic is also a threat to this species. A trail runs through the occurrence located on East Bay Regional Park's Point Pinole Regional Seashore. Foot traffic also is a potential threat to the largest occurrence of C. mollis ssp. mollis due to the increased urbanization occurring within 0.25 mi (0.4 km) of the population. Foot traffic disturbance through C. mollis ssp. mollis can easily damage the shallow and very brittle roots.

Cattle grazing continues on both private and state-owned tidal marsh lands adjacent to Hill Slough and in the privately owned tidal marsh near McAvoy Harbor. Extensive areas of bare ground are now present within these C. mollis ssp. mollis populations, substantially decreasing their numbers.

Oil spills are also an ever-present threat to C. mollis ssp. mollis occurring near Point Pinole. A hazardous waste clean-up effort resulted in the removal of a portion of the Middle Point population of this taxon in 1994. This population is found on the Concord Naval Weapons Station Property.

Cordylanthus mollis ssp. hispidus is a species generally associated with more alkaline habitats than the tidal marshes where C. mollis ssp. mollis is found. However, hybridization and mixing of traits may be occurring between these two subspecies, as possibly indicated in some voucher species kept in the University of California (Berkeley) and Jepson herbarium reference collections.

The risk of extirpation due to genetic and demographic problems associated with small populations is a threat to at least the two occurrences of C. mollis ssp. mollis that have fewer than 25 individuals. Additionally, the ongoing harvesting, planting of seed, and attempts at artificially expanding one of the populations in Contra Costa County, a project that is occurring without proper permits from the State of California, potentially threatens the genetic diversity of C. mollis ssp. mollis.

Conservation and Recovery

Only about 31 acres (12 hectares) of critical habitat of the soft bird's-beak survives in the San Francisco Bay area. Its second-largest population occurs on federal land managed by the Department of Defense (U. S. Navy). This critical habitat should be strictly protected from any threatening activities. Most other populations occur on private land and are potentially at risk from various kinds of developments. The largest of these critical habitats should be protected. This can be done by acquiring the land and establishing ecological reserves, or by negotiating conservation easements with the landowners. The populations of the soft bird's-beak should be monitored, and research undertaken into its biology and ecological requirements.

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
Telephone: (503) 231-6121
http://pacific.fws.gov/

U. S. Fish and Wildlife Service
Sacramento Fish and Wildlife Office
Federal Building
2800 Cottage Way, Room W-2605
Sacramento, California 95825-1846
Telephone: (916) 414-6600
Fax: (916) 460-4619

Reference

U. S. Fish and Wildlife Service. 20 November 1997. "Endangered and Threatened Wildlife and Plants: Determination of Endangered Status for Two Tidal Marsh Plants—Cirsium hydrophilum var. hydrophilum (Suisun Thistle) and Cordylan-thus mollis ssp. mollis (Soft Bird's-Beak) from the San Francisco Bay Area of California." Federal Register 62 (224): 61916-61925.