SENSITIVE JOINT-VETCH (Aeschynomene virginica) RECOVERY PLAN U.S Fish and Wildlife Service, Northeast Region Cover illustration, Aeschynomene virginica, used with permission of the artist Megan Rollins ~ 1994 SENSITIVE JOINT-VETCH (Aeschynomene virginica) RECOVERY PLAN Prepared by: Cynthia A. Schulz U.S. Fish and Wildlife Service Virginia Field Office White Marsh, Virginia for: U.S. Fish and Wildlife Service Region Five Hadley, Massachusetts Approved: Regional Director, Region Five c~f2c~ fc~< Date I ~I EXECUTIVE SUMMARY for the SENSITIVE JOINT-VETCH RECOVERY PLAN Current Status: The sensitive joint-vetch (Aeschynomene virginica) is known from 26 extant sites, including three in Maryland, one in New Jersey, two in North Carolina, and 20 in Virginia. The historical range for the species extended to Delaware and Pennsylvania. Although population sizes at the extant sites fluctuate considerably, there is an apparent trend for relative population size to remain stable. Almost every population of A. virginica is susceptible to habitat loss, modification, or degradation caused by development or water withdrawal projects. The sensitive joint-vetch was Federally listed as threatened in June 1992. Habitat Requirements and Limiting Factors: Aeschynomene virginica is an annual legume native to the eastern United States. The species occurs in fresh to slightly brackish tidal river systems, within the intertidal zone where populations are flooded twice daily. Its presence in a given marsh may be a factor of suppressed competition, hydrological conditions, salinity tolerances, and/or other parameters. A. virginica seems to favor microhabitats where there is a reduction in competition from other plant species. It typically occurs at the outer fringe of marshes or shores; its presence in marsh interiors may be a result of local nutrient deficiencies in the saturated organic soils, ice scouring, or muskrat herbivory. The sensitive joint-vetch is found in localities where plant diversity is high and annual species are prevalent. Bare to sparsely vegetated substrates appear to be a habitat feature of critical importance for establishmentand growth of this species. Recovery Objective: To fully recover Aeschynomene virginica, enabling its removal from the Federal list of endangered and threatened wildlife and plants. Recovery Criteria: Delisting will be considered when the following conditions have been met: (1) the sensitive joint-vetch and the ecosystems upon which it depends are adequately protected within the followingsix watersheds: Manokin Creek in Maryland; Manumuskin River in New Jersey; and Rappahannock, Pamunkey, Mattaponi, and Chickahominy Rivers in Virginia; (2) annual monitoring over a 10-year period shows that the populations in these six river systems are stable or expanding; and (3) life history and ecological requirements of the species are understood sufficiently to allow for effective protection, monitoring, and, as needed, management. Actions Needed: 1. Maintain the integrity of the tidal wetland systems upon which the sensitive joint-vetch depends. 2. Protect extant sensitive joint-vetch populations and sites. 3. Survey for additional populations. 4. Establish monitoring priorities, develop reliable monitoring techniques, and monitor populations accordingly. 5. Determine the ecological and distributional characteristics and requirements of the sensitive joint-vetch. 6. Develop an informational brochure on the importance of the sensitive joint-vetch and the tidal wetlands upon which it depends. Projected Costs ($000): FY NEED 1 NEED 2 NEED 3 NEED 4 NEED 5 NEED 6 TOTAL FYi 22.5 10.0 — 14.0 12.0 — 58.5 FY2 22.0 7.0 23.0 10.5 6.0 8.0 76.5 FY3 15.0 17.5 18.0 10.0 8.0 — 68.5 FY4-20 172.0 99.0 18.0 147.5 17.0 6.0 459.5 Total 231.5 133.5 59.0 182.0 43.0 14.0 662.0 Time Frame: Delisting should be possible by the year 2015 contingent upon accomplishment of recovery tasks. * * * The following recovery plan delineates actions believed to be required to recover and/or protect the threatened sensitive joint-vetch (Aeschynomene virginica). Attainment of recovery objectives and availability of funds will be subject to budgetary and other constraints affecting the parties involved, as well as the need to address other priorities. This approved plan does not necessarily represent the views or official position of any individuals or agencies involved in its formulation, other than the U.S. Fish and Wildlife Service. The plan is subject to modification as dictated by new findings, changes in species status, and the completion of recovery tasks. Literature citations should read as follows: U.S. Fish and Wildlife Service. 1995. Sensitive Joint-Vetch (Aeschynomene virginica) Recovery Plan. Hadley, Massachusetts. 55 pp. Additional copies of this plan can be purchased from: Fish and Wildlife Reference Service 5430 Grosvenor Lane, Suite 110 Bethesda, Maryland 20814 telephone 301-492-6403 or 1-800-582-3421 Cost varies according to number of pages. TABLE OF CONTENTS PART I: INTRODUCTION 1 Description and Taxonomy 1 Distribution and Status 3 Life History and Ecology 13 Threats to the Species 21 Conservation Measures 31 Recovery Strategy 35 PARTII: RECOVERY 37 Recovery Goal 37 Recovery Objective 37 Recovery Tasks 38 References and Literature Cited 47 PART Ill: IMPLEMENTATION 51 APPENDIX: LIST OF REVIEWERS LIST OF FIGURES AND TABLES Figure 1. Distribution of Aeschynomene virginica in the United States asof 1994 4 Table 1. Occurrence Records for Aeschynomene virginica in Maryland, NewJersey, North Carolina, and Virginia 5 PART I: INTRODUCTION The sensitive joint-vetch (Aeschynomene virginica) is an annual legume of the bean family (Fabaceae) native to the eastern United States. It occurs in fresh to slightly brackish tidal river systems in four mid-Atlantic states, where almost every population is subject to habitat loss, modification, or degradation caused by development or water withdrawal projects. Aeschynomene virginica was listed as threatened under provisions of the Endangered Species Act of 1973, as amended, on June 19, 1992 (U.S. Fish and Wildlife Service 1992), and was subsequently assigned a recovery priority number1 of 2, based on (1) a high degree of threat, (2) a high potential for recovery, and (3) its taxonomic standing as a species. This plan summarizes the relevant information currently available on Aeschynomene virginica, identifies threats to its survival and recovery, and specifies steps that should be taken to achieve recovery objectives. The recovery program for the sensitive joint-vetch is in its beginning phase. Initial efforts will include taking actions to offset imminent threats to the species’ survival and acquiring the information needed to effectively direct future recovery activities. DESCRIPTION AND TAXONOMY Aeschynomene virginica is a robust annual legume that typically attains a height of 1.0-2.0 meters (in) in a single growing season, although it may grow as tall as 2.4 m. The stems are single, sometimes branching near the top, with stiff or bristly hairs. The leaves are 1 Recovery priority numbers ranging from a high of 1 C to a low of 18 are determined for all species listed pursuant to the Endangered Species Act of 1973, as amended. These numbers are based on criteria defined in the Federal Register (Vol. 48, No. 184). A listed taxon with a ranking of 1 C receives the highest priority for the development and implementation of recovery plans. 1 even-pinnate, 2.0-12.0 centimeters (cm) long, with entire, gland-dotted leaflets. Each leaf consists of 30-56 leaflets. Leaflets are 0.8-2.5 cm long and 0.2-0.4 cm wide. The leaves fold slightly when touched. Pedicles are 3.0-8.0 millimeters (mm) long, bearing toothed bractlets about 4.0 mm long and 2.0-3.0 mm wide immediately below the flowers. The yellow, irregular, legume-type flowers are 1 .0-1 .5 cm across, streaked with red, and grow in racemes (elongated inflorescences with stalked flowers) 2.0-6.0 cm long. The flowers have uniformly- shaped anthers. The fruit is a loment with 4-10 one-seeded segments, the lowest 5.0-7.0 mm wide, turning dark brown when ripe. Fruits are 3.0-7.0 cm long, on a stipe 10.0-25.0 mm in length, and shallowly scalloped along one side. Aeschynomene virginica has been mistaken for other members of the genus, specifically A. indica and A. rudis. These two species, not native to the United States, have spread as far north as North Carolina in recent years, where their ranges now overlap with that of A. virginica. Aeschynomene indica is common in wet agricultural areas from North Carolina to Florida, and west to Texas and Arkansas. This misidentification has resulted in references to A. virginica in numerous weed science publications (e.g., Boyette et a!. 1979, Hackett and Murray 1986), but the situation was clarified by Carulli and Fairbrothers (1988), who showed the three species to be distinguishable based on electrophoretic analysis of allozyme variation. Previous studies had also indicated the morphological distinctiveness of A. virginica, and numerous other authors, including Fernald (1939), Gleason and Cronquist (1963), and Radford eta!. (1968), have recognized the taxonomic validity of A. virginica. The Vascular Flora of the Southeastern UnitedStates: Volume 3 (Isley 1990) clearly distinguished among Aeschynomene virginica, A. indica, and A. rudis. In her monograph of the genus, Rudd (1955) distinguished A. virginica from A. indica based on the sizes of the fruit stipes and the flowers. Ware (1991) offered the following to differentiate among these species: “The flowers, leaflets, and bractlets beneath the calyx of Aeschynomene virginica are all notably larger than those of Aeschynomene indica, and the fruiting pedicel is longer (10 to 25 mm versus 3.0 to 10 mm). One way Aeschynomene virginica differs from Aeschynomene rudis is by its wider lowermost legume segment (5.0 to 7.0 mm versus 3.0 to 5.0 mm).” In addition, A.