| Common Name | Stem |
Leaves |
Flowers |
General Characteristics |
Dodder Scientific Name: (Cuscuta spp.) |
Yellowish twining stem. |
Absent or reduced to fine scales. | White to pink cup-like flowers, numerous in compact clusters. | Parasitic annual that spreads by seed. Broadleaf plants serve as hosts, with alfalfa and clover being the most susceptible. Also called strangleweed for the thread-like yellow to orange twining stems that coil around and attach to host plants with wart-like suckers. Can produce over 16,000 seeds per plant that can remain viable for over 60 years |
| Eurasian Water Milfoil  Scientific Name: (Myriophyllum spicatum) |
Slender stems. |
Whorled, finely divided, feathery leaves. | Small, 4 petals and 4 sepals which quickly fall off, alternately arranged along the terminal ends of stems and attached directly to the stem. | Aquatic, mostly immersed in water. |
| Nodding Thistle  Scientific Name: (Carduus nutans) |
First year formas a large rosette, following year grows up to 2.5 m tall. | Leaves alternate spiny margins, deeply lobed, twisted or wavy. Dark green with light green mid-vein, woolly to densely hairy, up to 25 cm long. | Small pink to purple flowers clustered in a head to resemble a single flower, solitary at ends of branches. Below each head are several rows of spiny bracts | Biennial that spreads rapidly by seed forming extremely dense stands. |
| Yellow Star-thistle  Scientific Name: (Centaurea solstitialis) |
Erect, branching, rough, up to 1 m tall. | Lower leaves are deeply lobed, upper leaves have an entire margin and become smaller towards the top of the plant, fine hairs. | Small yellow flowers clustered in a head to resemble a single flower, solitary at ends of branches, sharp yellowish spines up to 2 cm long extend from below the flower head. | Annual that spreads by seed. Unable to utilize rangeland when yellow star-thistle is present. If grazed, causes a nervous disorder known as "chewing disease" that can result in death of the animal. |
| Diffuse Knapweed  Scientific Name: (Centaurea diffusa) |
Erect stems with numerous branches, up to 1 m tall | Leaves initially form a rosette, later become alternate, divided into narrow segments, rough, hairy, grayish-green | Small white to purple flowers clustered into a narrow head to resemble a single flower, solitary at ends of branches, prominent spines on head | Annual to short-lived perennial that spreads by seed. Commonly confused with spotted or Russian knapweed. However, diffuse knapweed is easily distinguished as the flower head is covered with prominent spines. Reported to exude chemicals which prevents the germination or establishment of neighboring plants. |
| Spotted Knapweed  Scientific Name: (Centaurea maculosa) |
Branched stem, up to 1 m tall. | Leaves initially form a rosette, later become alternate, divided into segments, slightly hairy. | Small pink to purple flowers clustered into a head to resemble a single flower, solitary at ends of branches, bracts with black tips. | Biennial to short-lived perennial that spreads by seed. Commonly confused with difuse or Russian knapweed. However spotted knapweed is easily distinguished by the "spotted" bracts on the flower head. Reported to exude chemicals which prevents the germination or establishment of neighboring plants. |
| Scentless Chamomile  Scientific Name: (Matricaria maritima) |
Highly branched, bushy, smooth, up to 1 m tall. | Alternate, very finely divided into thread-like segments, usually hairless. | White and yellow, daisy-like, solitary at the ends of long branches. | Elevated to noxious weed by the municipality. Annual or winter annual to short lived perennial that spreads by seed (4000,000 seeds/plant). Commonly confused with ox-eye daisy when in flower, but is easily distinguished by the finely divided leaves and bushy growth. Also confused with pineapple weed when flowers are absent, although easily distinguished by the lack of odor when leaves are crushed ("scentless"), while pineapple weed has a distinct fruity odor ("pineapple"). |