| | Red bartsia - Odontites serotina L
Source1:
Wisconsin State Herbarium, Emmet J. Judziewicz photograph |
Stem:
Erect, branching and bear clasping narrow leaves about 3 centimeters in length.
Leaves:
The leaves occur in pairs and taper to a point.
Flowers:
Spike-like clusters of flowers develop on flower stalks which grow from the point where the leaves join the stem. Most flowers are found on the top half of the stem. The blossoms are reddish-purple in color and resemble tiny snapdragon flowers (1 centimeter or less than 1/2 inch long).
General:
At maturity, an infestation gives a reddish tingle to hayfields, pastures or ditches. This reddish tinge is also seen in infestations of red samphire (Salicornia), a plant frequently found growing in ditches, and often confused with red bartsia. The two species can be distinguished by the absence of any leaves on red samphire. Red bartsia is prolific, producing about 1400 seeds/plant. The seed shells out in September, infesting fields for some time to come. Coarse hairs cover the seeds, enabling them to adhere to clothing and equipment. The seed is light and is easily carried along ditches and through fields by runoff water.2 |
Diffuse knapweed - Centaurea diffusa L.
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Stem:
Erect stems with numerous branches, up to 1 m tall
Leaves:
Leaves initially form a rosette, later become alternate, divided into narrow segments, rough, hairy, grayish-green
Flowers:
Small white to purple flowers clustered into a narrow head to resemble a single flower, solitary at ends of branches, prominent spines on head
General:
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 - Centaurea maculosa L.
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Stem:
Branched stem, up to 1 m tall.
Leaves:
Leaves initially form a rosette, later become alternate, divided into segments, slightly hairy.
Flowers:
Small pink to purple flowers clustered into a head to resemble a single flower, solitary at ends of branches, bracts with black tips.
General:
Biennial to short-lived perennial that spreads by seed. Commonly confused with diffuse 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.
Small pink to purple flowers clustered into a head to resemble a single flower, solitary at ends of branches, bracts with black tips. |
Nodding thistle - Carduus nutans L.
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Stem:
First year forms a large rosette, following year grows up to 2.5 m tall.
Leaves:
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.
Flowers:
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
General:
Biennial that spreads rapidly by seed forming extremely dense stands. |
Eurasian Water Milfoil - Myriophyllum spicatum L.
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Stem:
Slender stems.
Leaves:
Whorled, finely divided, feathery leaves.
Flowers:
Small, 4 petals and 4 sepals which quickly fall off, alternately arranged along the terminal ends of stems and attached directly to the stem.
General:
Aquatic, mostly immersed in water. |
Dodder - Cuscuta spp.
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Stem:
Yellowish twining stem.
Leaves:
Absent or reduced to fine scales.
Flowers:
White to pink cup-like flowers, numerous in compact clusters.
General:
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. |
Yellow star-thistle - Centaurea solstitialis L.
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Stem:
Erect, branching, rough, up to 1 m tall.
Leaves:
Lower leaves are deeply lobed, upper leaves have an entire margin and become smaller towards the top of the plant, fine hairs.
Flowers:
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.
General:
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. |
Reference:
Weed glossary adapted from Weed Management – Telus, Alberta Ag Fieldmen Association, Ducks Unlimited – D. Bigelow, B.Vanden Born, S. Bayley contributors
1Red bartsia picture source: Wisconsin State Herbarium, Emmet J. Judziewicz photographer
2Red bartsia information from Manitoba Agriculture
Pictures courtesy MD of Willow Creek unless otherwise noted
Prepared by Colin Bergstrom, Alberta Ag-Info Centre, Alberta Agriculture and Rural Development |
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