June 26, 2014
Common Milkweed, Asclepias syriaca
This is the largest of several native milkweed species that can be found at Fresh Pond Reservation. Milkweeds are the host plant for the larvae of the much-loved Monarch Butterfly. The larvae ingest chemicals from the plants that make them unpalatable for birds, which quickly learn to leave them alone. Monarch populations are in decline, partly, it is believed, because farmers are using more herbicides in their fields, eliminating weeds such as the milkweeds. Another threat is the explosion of the non-native vine called Black Swallowwort, Cynanchum louiseae. Although it is a milkweed relative, it contains chemicals that kill the butterfly larvae.