There are already a few noxious weeds you might spot flowering around here this month. Just today I noticed flowers on a spurge laurel plant I have potted up for education events.
Spurge laurel (Daphne laureola) is a smallish evergreen shrub that looks like a weird cross between a rhododendron, a laurel, and a plant from a Dr. Seuss book. The flowers are not obvious, being tucked in to the leaf axils near the stem, greenish in color, and lacking the sweet odor of its cousin Daphe odora. Like all Daphne species, spurge laurel has an irritating sap and the whole plant is toxic to people, pets and other animals.
The plant itself is not difficult to pull up when it is on its own, although the roots can be deep and it is critical to wear gloves to avoid irritation from the sap. Larger infestations will be much more difficult and time-consuming to control, so it’s best to watch for it and catch it before it gets established. Spurge laurel isn’t required for control in King County, but it isn’t that widespread so it really should be controlled if at all possible.
Another noxious weed I spotted recently is a very different sort of plant. Common groundsel (Senecio vulgaris) is an extremely common, small annual plant that can be found flowering almost year round and spreads by little dandelion-like seeds.
It is as toxic as its larger cousin tansy ragwort but much less conspicuous. This is probably why it more often ends up in hay, where it can sicken horses and cattle. The plant is so common and widespread that it really makes no sense to try to control it everywhere. However, hay growers and horse and cattle owners should be vigilant about watching for it near hay fields and pastures. Like most annuals, it is encouraged by soil disturbance and is most common on edges of fields, roads, and gardens. Small plants can be hoed out or smothered with mulch, ideally before the flowers form since it forms seeds soon after flowers appear.
A third noxious weed usually starting to flower this month is gorse (Ulex europaeus).
This is a tall, robust, spiny shrub that resembles Scotch broom. The flowers are golden yellow and fragrant and grow densely all over the plant. Two unpleasant things about gorse are that it doesn’t really have leaves but instead is covered with stiff, sharp spines, and that it contains a volatile oil that makes it very flammable. We don’t have a lot of gorse in King County so it would be very helpful to find out where it is growing if you do spot any.
And finally, I just noticed a few flower buds emerging on a European coltsfoot (Tussilago farfara) plant (that I also have handy for education purposes).
This species is new on our state noxious weed list and a high priority for control. It sends up flowering stems before its leaves appear later in the year. The flowers are bright yellow and daisy-like and grow on leafless stems and it can look very strange to see these bright yellow flowers appear out of bare mud. We are very interested in finding locations of this plant in our county, so please let us know if you see any.
If general if you spot noxious weeds growing anywhere in the United States, you can use the handy EDDMapS website or one its apps (for our area use EDDMapSWest) to add the location to a national database of invasive plants, which helps scientists track where different species are growing around the country. If the location is in King County, we will get a notification, and if it is a regulated noxious weed here, we will even follow up and make sure it is controlled. If you are unsure what a plant is, you can always email us a photo and we will do our best to identify it for you.