milk vetch
noun
: any of a genus (Astragalus) of annual or perennial leguminous herbs of north temperate regions
Example Sentences
Recent Examples on the Web Overall, fewer than 3,000 individual Braunton’s milk vetch plants persist in a region spanning about 80 miles from east to west and 25 miles from north to south. 
Louis Sahagunstaff Writer, Los Angeles Times, 1 Aug. 2019
Louis Sahagunstaff Writer, Los Angeles Times, 1 Aug. 2019 Word History
Etymology
from the popular belief that it increases the milk yield of goats
First Known Use
1597, in the meaning defined above