Archive - Weed of the Month - Bannock County Noxious Weed Control

Archive - Weed of the Month

Rush Skeletonweed

Photo courtesy of www.fs.usda.gov

Perennial or biennial, up to 3 feet tall with wiry branched flower stems; lower stems have dense, bristly, downward-pointing hairs; milky sap.
Basal rosette leaves are lance-shaped, shallow lobed, with a pointed terminal lobe and lateral lobes opposite and usually pointing backward toward the leaf base; stem leaves are bractlike, often lacking.
This plant has a taproot and lateral roots.
Flowers are bright yellow, strap-shaped, in axils or at the ends of branches.
Seeds are pale to dark-brown ribbed achene, disperse long distances in canyons, likely 1-5 miles, and survive fewer than 5 years.
Grows well on roadsides, rangelands, pastures, and grain fields.

Burr Buttercup

Winter annual that emerges, flowers, and sets fruits in the spring.
2 or 3 inches tall, often in dense mats covering large areas of ground.
Flowers usually have 5 bright yellow petals and are less than 1/4 inch long.
Seeds are contained in a burr, 1/2 - 3/4 inch long, that develops from the blossom and changes from green to brown and dries out.
Leaves resemble a bird's foot, divided into finger-like segments and covered with fine hairs.
Stems are short and leafless and the plant has a small taproot.
Widespread in gardens, small grains, pastures, waste areas, and along roadsides.
HIGHLY TOXIC - especially when crushed.

Hoary Cress -
aka Whitetop

Photos courtesy of Weeds of the West.

Perennial; grows up to 2 feet tall.
Flowers are numerous, white, tiny, 4-petalled; in dense clusters at the top of each stem.
Leaves are gray-green, lance-shaped, with hairy surfaces.
Seeds are small, flat, and reddish brown inside upside-down heart-shaped, often 2-lobed pods.
Seeds remain viable for about 4 years.

Kochia

Although Kochia is not on the Idaho Noxious Weed list, it is very common and can cause a lot of problems with road and parking lot maintenance.

An annual plant with a deep taproot and grows 1 1/2 to 5 feet tall.
Stems are upright, branched and have hairs on the upper parts of stems, sometimes tinged red.
Leaves are alternately arranged and are 1 to 2 inches long. They are narrow to lance shaped with smooth, hairy edges and may have silky hairs on leaf undersides.
Flowers are small and green, grouped in clusters in the upper leaf axils and on terminal spikes.
Each flower forms a small inflated seed bearing structure that is covered by the sepals. Seeds are wedge-shaped and light brown.
Kochia reproduces from seeds, it typically produces around 14,600 seeds per plant. Seeds are dispersed in the fall when the plant becomes a tumbleweed.
These plants are found on pasture, rangeland, roadsides, ditch banks, wastelands and cultivated fields.

White Bryony

Climbing perennial vine up to 50 feet in length with tendrils.
Thick, fleshy roots that resemble a large turnip.
Leaves are palmately 5-lobed, triangular, up to 5 inches long, and rough to the touch.
Flowers are greenish-white, 5-petaled, 1/2 inch across, and in clusters in the leaf axils.
Seeds are a spherical berry, 5/16 inch in diameter, green turning to black when mature.
ALL PARTS OF THE PLANT ARE POISONOUS, BUT ESPECIALLY THE ROOT!
Grows up power poles, fence rows, and trees.
Seeds disperse long distances by birds.
Resembles kudzu and native clematis in its growth habit.
Please help us find these aggressive weeds! Give us a call if you find one.

Salt Cedar

Shrub or small tree up to 24 feet tall.
Long taproot with lateral roots.
Leaves are small, scale-like, gray-green & overlapping along the stem.
Flowers are pale or dark pink with 5 distinct petals; inflorescence panicle-like.
Seeds are a capsule with a tuft of long hair.
Exudes salt from foliage.
Root & stem fragments float on water for medium to long-distance dispersal.
Seeds disperse at least 100 yards in light wind & remain viable less than 1 year.

Leafy Spurge

Erect perennial up to 2 1/2 feet tall with roots exceeding 20 feet in depth.
Milky sap is toxic to humans & livestock.
Flowers are a pair of showy, yellowish-green, heart-shaped bracts with tiny flower clusters.
Leaves are nearly opposite & narrow.
Roots are long, both vertical & horizontal. Creep horizontally.
Seeds disperse less than 15 feet & remain viable for at lease 8 years.