Asclepias fascicularis

Identification

Description

Narrow-leaved Milkweed has narrow leaves and a wider native range and a whole lot more garden tolerance than most of the other native species. Asclepias fascicularis is a perennial with three foot tall stem and large (but narrow) five inch leaves, and a five inch or so flower cluster. In our area, this plant is covered with monarch caterpillars during the summer. The Orioles use the dead stems for nests the next spring. (The matter looks like fiberglass.) Milkweeds need sun (less flowers in the shade) and can be quite drought tolerant, plant, mulch heavily,or better yet, plant next to boulder, water well first month and ignore. Asclepias fascicularis can tolerate some pretty awful coastal clays that are sour bogs in winter and salty toast in summer. Native from Southeast Washington and adjacent Idaho through California,Oregon into Baja California and west into Nevada. Although Milkweeds can be poisonous to cattle, it is more of a management issue, not a poisonous one. If they have nothing to eat but milkweed it's a problem, and occasionally you'll get a druggy that prefers milkweed to anything else. Different alkaloid than cocaine, similar effect. The alkaloids associated with this plant give the butterflies that feed on it protection. Alkaloids from the wrong milkweed(South American, Mexican, etc.) can expose the butterflies to predation. If the monarch or other butterfly has not evolved with the milkweed they have no tolerance for the particular alkaloid of the species. The California flyway runs from Baja to Canada, it does not include Mexico proper nor Central America. If you live in Chicago you can plant Mexican species (Asclepias mexicana) or Asclepias tuberosa, don't plant our species. I would guess the symptoms to be similar to the problem of intolerance to legumes that some people have. Larval food plant for the Monarch butterfly.