Weed Identification Flashcards Preview

OH - Turf and Ornamental Weed Management Principles & Thirty Common Ornamental Weeds in Idaho > Weed Identification > Flashcards

Flashcards in Weed Identification Deck (30):

Vigorous annual with considerable variation. Grow up to 3 ft in some areas, 6 - 8 in. In other areas. Stems may be erect or restin on the ground.



Bright or pale green, tufted annual grass with soft foliage. Plants reach a height of 4 - 8 inches often root at the lower nodes of prostrate stems.

Annual Bluegrass


An annual or winter annual that reproduces only by seed. The plants are usually 10-15 inches high, although viable seeds may develop on plants no more than 2 inches high. The leaf blades and sheaths are hairy.

Downy brome


Perennial with u branched stems commonly 1-3 feet high; leaf blades are flat, thin, and form 1/4 to 1/2 inch wide. Leaf sheath and blades may be thinly covered with soft hairs or sometimes with whitish, powdery bloom, but are mostly w/o the hairy covering.



Annual with stems that are often prostrate at the base. the plants vary in height from 1/2" to 2 1/2'. Both leaves and stems have conspicuous hairs. The diffuse panicle is densely flowered and produces an abundance of seeds. The individual grains are tiny and enclosed in the flowering scales.



Perennial from slender rootstocks and thick taproots with milky sap. The stems are slender, erect, and 2 - 3 feet high or more. The lower leaves are occasionally heart-shaped, the stem leaves are narrower, 2 - 4 inches long, irregularly serrated on the margins. The bell-shaped flowers are blue, about 1 inch long, and nodding on the stem.

Creeping Bellflower


Perennial from deep-seated taproot, which gives rise to several or numerous slender underground rhizomes or prostrate, twining stems. The leaves are alternate and arrow-shaped mostly about 1 - 2 inches long. White or pink bell-shaped flowers, frequently as much as an inch in length, are borne on stalks about 1 inch long, which rise from axils of the leaves.

Field bindweed


Perennial with milky juice from a long, deep taproot with stems from 1 - 4 feet high. The leaves are alternate, rough and hairy, the lower leaves are deeply cut and large with the stem. The flowering heads are about 1 1/2 inches broad with several blue, rarely pink or white flowers in each head.



Annual or winter annual with much branched creeping or ascending branches with a conspicuous line of hairs on one side. The plants may root at the nodes and form mats. The leaves are broadly oval and pointed. Those on the lower part of the plant have definite stalks while those higher on the branches do not. Flowers are no more than 1/4 inch across with petals somewhat shorter than the sepals. Capsules are many seeded, extend beyond the sepals and open by six teeth.

Common chickweed


Perennial from a stout taproot with ridged stems up to 3 feet high. Leaves are 4 to 12 inches long and have a way and curly margin. The flowers are small and in dense, brown clusters. The fruits are reddish-brown, triangular, and nearly 1/10 inch long. The waving and curled leaf margin will serve as the key character.

Curly dock


annual or biennial with spreading or nearly prostrate stem. The leaves are much dissected with paired stipules at the base of the leaf stalks. The flowers are pink to purple and in umbrella-like clusters. There are five sepals and each one is bristle tipped. The fruit is made up of five parts that become separated at maturity. The long styles appear as tails on the fruits and become spirally twisted when dry.

Redstem filaree


A creeping or trailing perennial with flowers much like those found in catnip.

Ground ivy


Prostrate mats that become much branched with maturity. The leaves are bluish-green in color, thin, and with an acute apex. Inconspicuous rose colored flowers appear in the axils of the leaf. The fruits "seeds" are three angled and a dull brown to black. Parts of the flower will usually remain attached to the fruits.

Prostrate knotweed


Erect annual that becomes much branched. the species is highly variable in color and form. Spherical and pyramidal plants in colors of varying green to reds are often grown in our gardens and escape from cultivation. The leaves are placed alternatively on the stem and usually have conspicuous hairy margin. The small flowers are in axillary clusters and the individual flowers have a five lobed calyx that develops into wing like appendages.



This species is an annual from 1 to 6 feet high with ridged, green, or sometimes reddish-striped stems. Leaves are highly variable in shape but usually somewhat triangular in online with coarsely toothed margins. The lower leaf surface is grayish green and densely covered with mealy particles. The small flowers are crowded in the leaf axils and at the stem tips. Each flower develops a tiny, single shiny black seed that is often covered by a white papery envelope, the calyx.

Common lambsquarters


Biennial or winter annual with milky juice. The stems arise from a taproot and may vary in height from 1 to 5 feet. The leaves are alternate, deeply divided, and clasping the stem with pointed ear-like projections. The flowering heads are numerous, with bracts that elongate at maturity. The flowers of the head are all strap-shaped ray flowers, yellow and turn bluish with age. The seeds are roughened, contracted abruptly on top to form a beak with a parachute of bristles above.

Prickly lettuce


Annual, winter annual, or biennial with many spreading or procumbent stems from a deep taproot. The leaves are nearly round in outline with a heart-shaped base and paired stipules at the base of the leafstalks. Flowers are whitish, with the well known hollyhock form. The fruits are arranged in a ring and are mucilaginous.

Common mallow


annual or winter annual with branched prostrate stems and trifoliate leaves. The plant looks much like a clover, but the terminal leaflet is on a short stalk placing it beyond the pair below while the three leaflets in a clover arise from a common point. The flowers are small, yellow, and in dense short spikes. The pods become strongly curved and ordinarily mature with one seed.

Black medic


Coarse, erect annual from 2 - 3 feet high with reddish taproots. The leaves are long stalked, dull green; the lower surface has prominent light-colored veins. The flowers are numerous, green, crowded into dense terminal spikes and also in the leaf axils below. Each flower is enclosed in three bracts that produce the bristly appearance of the spike. The seeds are a shiny black and no more than 1/23 of and inch broad.

Redroot pigweed


Relatively short five to seven ribbed leaves. The flowering spike is slender and somewhat long, and the seeds are small and angled.

Broadleaf plantain


Perennial from a deep-set stout taproot, the crown of which produces a rosette of leaves each year. The leaves are lance-shaped, 3 - 6 or even 12 inches long, coarsely three to five ribbed, and hairy or nearly smooth. the greenish-white flowers are borne on a naked stem, some 6 - 12 or 15 inches long, and form a dense, cylindrical, short, cone shaped spike. The capsules dehisce in the middle with the top coming off like a lid. The seeds are less than 1/8 inch long, elliptical, shiny, brown, and with a scar on the concave surface.

Buckhorn plantain


Prostrate, trailing vine, the hairy branches radiating from a slender taproot. When support is available, the plant readily becomes a scrambler or climber. The leaves are mostly opposite and compound with four to seven pairs of oval or elliptic leaflets which are about 1/2 inch long. the flowers are produced silly on long stalks arising from the axils of leaves. the yellow flowers have five petals about 1/2 inch long, and 10 stamens. The fruit is a five-part bur , which readily breaks into wedge-shaped two-horned segments at maturity, each somewhat more than 1/4 long.



annual with prostrate, fleshy stems and leaves. Matured plants often have a reddish color and from large, intricately branched mats. The lower leaves are placed alternately on the stems, while those above are in dense clusters. the flowers are produced in the leaf axils and have five yellow petals that are open on sunny mornings. The seed capsules are small and loaded with numerous black, tiny seeds. The capsule looks like a lead bud and opens below the middle by a lid exposing the matured seeds.

Common purslane


biennial that becomes branched in well developed plants. The stems are 1 - 3 feet high and have long, narrow, grass-like alternate leaves. The branches have single large head. The flower stalks become enlarged under the heads. The flowers in a head are pale yellow, all strap-shaped ray flowers that are surpassed by the narrow leaf-like bracts. The seeds taper to a slender beak that is topped by a tawny or whitish papas of interwoven plumose bristles that from the parachute.

Western salsify


Annual or winter annual. Robust plants become much branched and often reach heights of more than 3 feet. Basal leaves often occur in dense rosettes and vary considerably in form, from deeply cleft to nearly entire. Stem leaves are also variable in form, but are always stalkless and clasping with ear-like projections. The flattened pods are about 1/4 inch long, triangular in outline, and notched on top.



Annuals that reproduce by seed. The flowers are quite similar in all of the species studied here, with four united petals that vary in color from white, pale blue, to lavender. The petals and two attached stamens come off readily.



common weeds of gravelly driveways, cultivated areas, or in poorly established old lawns. They are much branched annuals often with relish stems. Vigorous plants often have an expanded area above the annual root system where the numerous branches take off. Specimens growing under ideal conditions may attain a diameter of2 to 3 feet and produce hundreds of viable seeds.

Prostrate spurges


Coarse, prickly, biennial plant, usually 2 to 3 feet or more in height. The leaves sometimes appear in a large rosette during the first year. In the second season, a flowering stem develops. The stem leaves are lance-shaped, smaller than the basal, but otherwise similar. They are variously deeply and sharply lobed and toothed, and are quite hairy beneath. The heads are mostly terminal, single, and large, sometimes 3 inches across, and produce numerous purplish tubular flowers.

Bull thistle


Produces extensive coarse and branching rhizomes which give rise to numerous stems from 1 to more than 4 feet tall. The leaves are alternate, lanceolate, or oblong in outline, strongly and irregularly lobed with spiny-toothed margins. The small, tubular, usually purple flowers are aggregated in the heads which are about 1/2 inch across and which are arranged in a flat-top inflorescence.

Canda thistle


An annual or occasionally a perennial weed with sour watery juice. The stems sometimes branch at the base, and are occasionally decumbent. The leaves have three leaflets, each leaflet heart shaped. The flowers are less than 1/2 inch long, yellow, and sometimes relish at the base. The fruit turns down at maturity, about 3/4 inch long and five celled in cross section.

Yellow woodsorrel