Overview
Ventura marsh milk-vetch (Astragalus pycnostachyus var. lanosissimus) is a short-lived perennial shrub in the pea family (Fabaceae) that lives about five years. Endemic to coastal Southern California, this species was historically found in Los Angeles and Ventura counties and was introduced to Santa Barbara County in the early 2000s. The species was presumed to be extinct when surveys in the 1960s and 1970s found no Ventura marsh milk-vetch populations or presumed suitable habitat. The species was later rediscovered in 1997 in Oxnard, Calif., when wildlife biologists found a strange milk-vetch in an oil disposal site that had been proposed for development; this unknown milk-vetch was later identified as Ventura marsh milk-vetch. State listed as endangered in 1999 and federally listed as endangered in 2001, this species is associated with coastal wetlands. Habitat loss and degradation played a major role in its initial presumed extinction. Currently, measures are being taken to reintroduce the species into suitable habitats using seeds from the plants of the rediscovered area. However, competition with native and non-native plants, herbivory, and climate change climate change
Climate change includes both global warming driven by human-induced emissions of greenhouse gases and the resulting large-scale shifts in weather patterns. Though there have been previous periods of climatic change, since the mid-20th century humans have had an unprecedented impact on Earth's climate system and caused change on a global scale.
Learn more about climate change are all challenges to successful Ventura marsh milk-vetch reintroduction.
Scientific Name
Identification Numbers
Characteristics
Habitat
The habitat of Ventura marsh milk-vetch is poorly understood. Historically, it had been associated with cienegas (freshwater alkaline wet meadows), seashore meadows and salt marshes. The California Natural Diversity Database describes the habitat for this species as coastal salt marsh salt marsh
Salt marshes are found in tidal areas near the coast, where freshwater mixes with saltwater.
Learn more about salt marsh that is protected by barrier beaches or is near the high tide. However, this description is based on the habitat of the closely related species, coastal marsh milk-vetch (Astragalus pycnostachyus var. pycnostachyus). None of the remaining populations occur under entirely natural conditions; the only unplanted population exists in a heavily modified oil waste disposal site maintained via supplemental watering and the control of competing plants. The remaining populations are all planted with the seeds from the rediscovered site and exist in coastal wetland habitats. Plans for recovery of the species include identifying appropriate coastal wetland habitat with proper conditions. As such, more research is needed to understand the habitat of this species.
Areas such as marshes or swamps that are covered often intermittently with shallow water or have soil saturated with moisture.
Physical Characteristics
Ventura marsh milk-vetch (Astragalus pycnostachyus var. lanosissimus) is a short-lived perennial shrub that can reach up to 2 meters in height. During winter, it produces leafy stems from a woody root crown that is visible on some individuals. Flowering in the summer, this species produces about 31 to 40 flowers per inflorescence (flower cluster). The fruit it produces is relatively small for the genus and is slightly curved. The leaves of this species are compound leaves and are composed of 27 to 39 leaflets per leaf.
Measurements:
Stem height: 106 cm to 170cm (42 inches to 67 inches)
The leaves of the species are a muted sage green color. During the summer, it produces flowers that are pale yellow with possible tinges of green. New stems are green, while stems exposed to direct sunlight have a dark maroon color. Individuals in shaded areas have a green stem color. Additionally, stems that are partly shaded beneath other plants will be green, while portions of the stem that are exposed to the sun will be maroon.
Life Cycle
During the winter, this species produces leafy stems. Buds begin to appear on inflorescences, flower clusters, on these stems starting in mid-June, with flowers opening as early as late June and as late as early September. However, peak flowering occurs during mid-July. By early September, most of the flowers mature into fruits. The stems die as winter approaches, and it is common for some fruits to remain attached to these stems into the following year. The fruits usually disperse near the parent plant. Germination occurs following periods of heavy rainfall. If successful germination does occur, seedlings will emerge as early as 16 days and can emerge as late as 42 days, with most emerging before the 24-day mark.
Similar Species
There are two varieties of Astragalus pycnostachyus. These varieties are allopatric; existing in two separate non-overlapping areas. The northern variety, coastal marsh milk-vetch (Astragalus pycnostachyus var. pycnostachyus), occurs in Marin, San Mateo and Humboldt counties while Ventura marsh milk-vetch historically occurred in Los Angeles and Ventura counties. Both varieties are associated with coastal wetlands.
Geography
Endemic to Southern California, Ventura marsh milk-vetch was historically found along the coasts of Los Angeles and Ventura counties. In 1997 when the species was originally rediscovered, only one population in Ventura County was known. Since its rediscovery, several attempts have been made to restore the species at various locations. Currently, only four populations with reproductive individuals exist. One is the “natural” rediscovery site at North Shore in Oxnard. The remaining populations are the McGrath parcel in Oxnard, the University of California, Santa Barbara (UCSB) North Campus Open Space and the UCSB Carpinteria Salt Marsh Reserve. With these introduced populations, the current range of this species is coastal areas in Ventura and Santa Barbara counties. UCSB populations are north of its historic range and was established at this site in anticipation of climate impacts.
Timeline
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