Beware of a pretty purple-blue flower that is blooming and producing seeds in unsuspecting public sites, homeowners’ gardens, along the alleys, disturbed grassy areas, and unmowed roadsides. Bird Vetch (Vicia cracca) is an invasive, harmful weed that spreads rapidly by seed and underground roots. It climbs over other flowers, grasses, and shrubs, and up fences and small trees. When it gets established, it turns into an uncontrollable monster. Perhaps you have noticed it smothering the vegetation along the highway from Girdwood to Anchorage.
The small 3/4 to 1″ purple-red, pea-like flowers grow in a dense, one-sided cluster of 20-50 flowers. The leaves have 10-20 leaflets which are very narrow, and have climbing tendrils. A similar plant is the native Beach Pea, which has much larger flowers that do not grown in dense clusters, and whose leaflets are much wider. It grows in a low mound, never climbs, and is not a weed.
If you find this pretty but nasty Bird Vetch, please pull it immediately, put it in a sturdy plastic bag, tie it securely and put in the trash. Fortunately, it is easy to pull and the flowers do not go to seed like dandelions after being pulled.
The best way to control this invasive perennial is to mow and hand pull before it produces seeds. If you recognize the plant, pull it. If you’re not sure, pull it as soon as you see those pretty flowers, before they produce seeds. Luckily, the seeds only live about 5 years, so once it gets started, the plants have to be pulled every few weeks until all the seeds are germinated. This will have to be done for 6 years. It seems like a long time to monitor the infested area, but as seeds go, this is a manageable, short time, and so worthwhile.
Grass clippings can also be used to smother weed-infested sites, such as along the alleys, after pulling the plants. A thick mat of grass clippings will eventually compost, allowing you to plant more desirable plants.
Seward has hot spots like the Middle School, ROWs along Third Ave from Van Buren to Port Ave, and some alleys, but we still have a chance to control it before it overtakes our beautiful wildflowers and landscaping.
Another nasty noxious weed is Hemp Nettle, Galeopsis tetrahit. This plant is on the prohibited noxious weed list in Alaska. A member of the mint family, it has either white or purple small flowers, bristly square stems, and opposite leaves. This plant pulls easily as well, but gloves are recommended due to the prickly stems and seed pods. Pull it as soon as you see it, the earlier the better, before it produces seeds.
It is extremely important that these weeds and all other weeds be immediately placed in a plastic bag to prevent the unintentional spread of seeds. Tie the bag securely and throw in the trash for disposal.
There is more information on the internet, including a link to the UAF Cooperative Extension Service at 1-877-520-5211, www.uaf.edu.ces.
Note: this article was first posted on July 15, 2015 but a reminder was requested. The article was revised and updated.