The weeds listed below have been identified as noxious, requiring some measure of control by Deschutes County.  These weeds occur in Crook and Jefferson Counties as well, but may have a different category designation.  Contact the County Weedmaster for your area for more information on specific weed law and regulation.

Deschutes County has categorized these weeds as "A, B or C" and has described each category as follows:

A.	An 'A' designated weed is:  a priority noxious weed designated by the Deschutes Weed Board as a target weed species.  An "A" rated weed may also be a weed of known economic or ecological importance which occurs in small enough infestations to make eradication/containment possible; or one that is not known to occur here, but its presence in neighboring counties make future occurrence here seem imminent.
B.	A 'B' designated weed is:  a weed of economic importance, which is both locally abundant and abundant in neighboring counties.
C.	A 'C' designated weed is:  a weed that has the potential to cause harm to agriculture production and transportation systems.

Thumbnail (click for more pictures)	Common Name	Latin Name	Deschutes County Designation	Description
	African Rue	Peganum Harmala	A	A much-branched perennial herb. Leaves are alternate, smooth and finely and deeply cut or divided with long, narrow segments. Flowers have 5 white petals. The fruit is a 2 to 4 celled, many seeded capsule.
	Buffaloburr	Solanum Rostratum	A	This native annual grows to 2 feet high, has leaves 2 to 5 inches long with deep lobes and is covered with spines. Yellow, 5-lobed flowers, common throughout the summer, are about 1 inch wide. The berry is enclosed by an enlarged calyx and contains many seeds. Seeds are black, wrinkled and flattened.
	Bull Thistle	Cirsium Vulgare	C	A biennial with a short, fleshy taproot. The stem is 2 to 5 feet tall, bearing many spreading branches. It is green or brownish, sparsely hairy, irregularly and spiny winged. Leaves in the first year form a rosette, stem leaves are pinnately ribbed, hairy and prickly on upper side and cottony underneath. Flowers are 1 1/2 to 2 inches wide, more of less clustered at the ends of branches. Seeds are topped by a circle of plume-like white hairs. Flowering occurs from July to September.
	Bur Buttercup	Ranunculus Tesiculatus	C	A low growing annual, 2 to 5 inches tall. Grayish-green leaves are basally attached, 1 to 4 inches long, with blades divided into finger-like segments. Yellow flowers, 5 petals, develop into stiff brown burs about 1/2 to 3/4 inch in length. Highly toxic to sheep.
	Canada Thistle	Cirsium Arvense	B	Canada thistle is a colony forming perennial from deep and extensive horizontal roots. Stems are 1 to 4 feet tall, ridged, branching above. Leaves are alternate, lacking petioles, oblong or lance-shaped, divided into spiny-tipped irregular lobes. Flowers are unisexual, on separate plants; flowers purple in heads 1/2 to 3/4 inch in diameter; involucral bracts spineless. Fruits are about 1/8 inch long, somewhat flattened, brownish, with a tuft of hair at the top. This aggressive weed is difficult to control; for example, breaking up the root by plowing only serves to increase the number of plants. Flower occurs during July and August.
	Cheatgrass	Bromus Tectorum	B	Bromus tectorum is an erect winter- or spring- annual grass. The seedlings are bright green with conspicuously hairy leaves, hence the alternate common name, downy brome. At maturity the foliage and seedheads often become purplish before drying completely and becoming brown or tan. The species grows quickly in the spring and often matures and sets seeds before most other species. It typically grows 50-60 cm (20-24 inches) tall, with a finely divided, fibrous root system that may reach a depth of about 30 cm (12 inches). When environmental conditions are poor and/or when grazing animals crop the plants, cheatgrass plants that reach heights of just 5-10 cm (2-4 in) can still flower and produce viable seed. The stems are erect, slender, and glabrous or may be slightly soft-hairy. The nodding, open panicles with moderately awned spikelets are very distinctive. The spikelets readily penetrate fur, socks and pants and its seeds may thus be widely dispersed by people and animals.
	Common Houndstongue	Cynoglossum Officinale	A	Houndstongue is a biennial growing 1 to 4 feet tall and reproducing by seed. Leaves are alternate, 1 to 12 inches long, 1 to 3 inches wide, rough, hairy, and lacking teeth or lobes. Flowers are reddish-purple and terminal. The fruit is composed of 4 prickly nutlets each about 1/3 inch long. Rosettes form in the first year of the two year growth cycle. NOTE: Herbicides are most effective when applied at this growth stage.
	Common Mullein	Verbascum Thapsis	C	This biennial produces a large, thick rosette of fuzzy leaves the first year and a single, stout, erect stem, 2 to 6 feet tall, the second year. The leaves are alternate, overlapping one another, light green, densely woolly. Flowers are sessile, borne in long terminal spikes, sulfur yellow, 5 lobed and more an inch in diameter. Fruits are 2 chambered with numerous, small, angular, brownish seeds, 1/32 inch long. Common sight along river bottoms, in pastures, meadows, fence rows and waste areas. Because of the large number of seeds produced by each plant, it is difficult to control.
	Dalmatian Toadflax	Linaria Dalmatica	B	A perennial, up to 3 feet tall, reproducing by seed and underground root stalks. Leaves are dense, alternate, entire, upper leaves are conspicuously broad-based. Flowers are borne in axils of upper leaves and 2 lipped, 3/4 to 1 1/2 inches long with a long spur, yellow with and orange, bearded throat. Fruit a 2-celled capsule with many irregularly angled seeds.
	Diffuse Knapweed	Centaurea Diffusa	B	Diffusely branched annual or short-lived perennial, 1 to 2 feet tall, stems are rough to the touch. Leaves are pinnately divided; the reduced leaves of the inflorescence are mostly entire. Flowering heads are numerous and narrow. Flowers are white or rose or sometimes purplish; margins of involucral bracts are divided like the teeth of a comb, and bracts are tipped with a definite slender spine. Infests roadsides, waste areas and dry rangelands. Herbicides are most effective when applied during early growth stage.
	Dodder	Cuscuta Spp.	C	This parasitic annual lacks chlorophyll. Stems are yellowish, thread-like and twining, leaves are reduced to thread-like scales. Flowers are numerous in compact clusters, 5-parted and shallowly cupped, white to pink. Fruit is a 2 to 4 seeded globular capsule which is somewhat depressed on the top, seeds are small, oval, gray to red and 1/25 inch in length. Dodder seeds germinate on the soil surface and the resulting plant develops a small root system and 2 to 4 inch long thread-like stalk which attaches to green plants. Many broadleaf plants serve as hosts for this parasite, but alfalfa and clover are especially susceptible.
	Dyers Woad	Isatis Tinctoria	A	Dyer's woad is a winter annual, biennial or short-lived perennial; 12 to 48 inches in height. Leaves of dyer's woad are alternate, simple, petiolate, bluish-green with a whitish nerve on the upper surface o f the blade. The inflorescence has a flat top, petals yellow; fruit a pod, indehiscent, black or purplish brown and one-celled, containing a single seed appear during mid summer. Seedling plants appear in the fall. Herbicides are most effectively applied during this stage.
	Field Bindweed	Convolvulus Arevensis	C	Perennial from an extensive root system, often climbing or forming dense tabled mats. Stems are prostrate, 1 to 4 feet long. Leaves alternate, more or less arrowhead-shaped, pointed or bunt lobes at the base. The flowers are bell or trumpet shaped, white to pinkish, approximately 1 inch in diameter with 2 small bracts located 1 inch below the flower. Fruit is a small, round capsule, usually 4 seeded. It is a difficult to eradicate because of the long, deep taproot which can penetrate the soil to a depth of 10 feet. Seeds remain viable for up to 50 years. The flowering period is from late June until frost in the fall.
	Filaree Redstem	Erodium Cicutarium	C	A winter annual with showy pink to purple flowers that ranges from 4 to 20 inches in height. Redstem filaree is primarily a weed of turfgrass and landscapes that is found throughout the United States.
	Horseweed	Conysa Canadensis	C	Horseweed is an annual weed. Leaves are narrow and hairy and vary in length from one to six inches. Leaves are situated in alternate positions on the stem and can sometimes be toothed or jagged along the outer margin. The upright woody stems can be very tall (up to six feet) and appear 'bushy' towards the top. Although flowering is uncommon in turf situations, flowers are small with yellow centers.
	Hydrilla	Hydrilla Verticillata	A	Hydrilla is a submersed plant. It can grow to the surface and form dense mats. It may be found in all types of water bodies. Hydrilla stems are slender, branched and up to 25 feet long. Hydrilla's small leaves are strap-like and pointed. They grow in whorls of four to eight around the stem. The leaf margins are distinctly saw-toothed. Hydrilla often has one or more sharp teeth along the length of the leaf mid-rib. Hydrilla produces tiny white flowers on long stalks. It also produces 1/4 inch turions at the leaf axils and potato-like tubers attached to the roots in the mud.Management methods include herbicide, grass carp, and mechanical removal.
	Indian Sweetclover, White Sweetclover, Yellow Sweetclover	Meliloutus Indica, Melilotus Alba, Melilotus Sofficinalis	C	An annual, winter annual, or biennial legume normally growing 2 to 6 feet tall. Trifoliate leaves resemble those of alfalfa, except that leaflet margins are serrated halfway or more back from the tip. Flowers are small, yellow or white and arranged in many-flowered terminal and axillary racemes. Pods are 1 or 2 seeded, and cross ribbed.
	Kochia	Kochia Scoparia	B	Annual, 1 to 6 feet tall, stems much branched, round, slender, usually soft-hairy, but occasionally smooth, often red-tinged. Leaves alternate, lance shaped, entire 1/2 to 2 inches long, margins fringed with hairs; the upper surface is usually smooth, the lower surface usually covered with soft hairs; leaf blades with 3 or 5 prominent veins. Flowers are inconspicuous, sessile in the axils of upper leaves and form short, dense, bracted spikes. Seed wedge shaped, dull brown, slightly ribbed and approximately 1/16 inch long. Flowering and seed production may occur from July to October.
	Leafy Spurge	Euphorbia Esula	A	Perennial, up to 3 feet tall; reproduces by vigorous rootstalks and seed. Leaves are alternate, narrow, 1 to 4 inches long. Stems are thickly clustered. Flowers are yellowish-green, small, arranged in numerous small clusters and subtended by paired heart-shaped yellow-green bracts. Roots are brown, containing numerous pink buds which may produce new shoots or roots. The entire plant contains a milky juice. Seeds are oblong, grayish to purple, contained in a 3 celled capsule, each cell containing a single seed. An extensive root system containing large nutrient reserves makes leafy spurge extremely difficult to control.
	Meadow Knapweed	Centaurea Pratensis	A	Perennial; up to 3 1/2 feet tall with many branches. Lower leaves long stalked, entire, coarsely lobed, or toothed, middle and upper leaves without stalks or near so, entire or toothed, the uppermost leaves usually much reduced and entire. Flowers borne in large pink to purplish-red heads at the end of branches; involucral bracts deeply fringed, light to dark brown. Infests roadsides, waste areas fields and pastures.
	Mediterranean Sage	Salvia Aethiopis	A	An aromatic biennial, growing 2 to 3 feet tall. In the first season it develops a rosette of large grayish wooly leaves. In the second season the plant bolts, producing multi-branched stems with white to blue-green, wooly, felt-like leaves. Lower leaves have petioles, are lobed with coarsely-toothed blades 1/3 to 1 foot long. Upper leaves are smaller and clasp the stem. Flowers are yellowish-white, borne in clusters on profusely branched stems.
	Medusahead Rye	Taeniatherum Caput-Medusae	A	An aggressive winter annual 6 to 24 inches tall. Leaf blades more or less rolled, generally 1/8 inch wide or less. Inflorecence a long awned spike that is nearly as wide as long. Mature awns twisted, 1 to 4 inches long, stiff, and minutely barbed. Flowering and seed formation occur in May and June. Medusahead is a highly competitive plant that crowds out all other vegetation on infested range land.
	Musk Thistle	Carduus Nutans	A	Musk thistle is a biennial or sometimes a winter annual, which grows up to 6 ft tall. Leaves are dark green with light green midrib, deeply lobed, and spiny margined. Leaves extend on the stem giving a winged appearance. Flower heads are terminal, solitary, 1 1/2 to 3 inches in diameter, and usually bent over. Flowers are deep rose, violet or purple, occasionally white; they are subtended by broad, spine-tipped bracts. Fruits are 3/16 inch long, shiny, yellowish-brown with a plume of white hair like fibers. Chemical control is effective. An introduced biological agent, the musk thistle weevil, feeds on the seeds an can limit the spread of this plant.
	Myrtle Spurge	Euphorbia Myrsinites	B	Myrtle spurge is a biennial or perennial. The plant grows from a taproot, with new stems emerging in early spring and dying back in the winter. Myrtle spurge has trailing stems, growing close to the ground. Stems and leaves are fleshy and grayish-green in color, and the leaves are attached to the stems in close spirals. Inconspicuous flowers, with showy yellowish bracts, are borne in clusters at the ends of the stems. Flowering occurs in March and April. Like other euphorbias, the plant contains a milky sap. Plants can grow up to 8-12 inches high and 12-18 inches in width.
	Orange Hawkweed	Hieracium Aurantiacum	A	Fibrous-rooted perennial with milky juice and above ground runners grows 30 to 60 cm tall; leaves mostly basal; leafless flowering stalk covered with stiff, black, glandular hairs; vibrant orange-red flowers.
	Perennial Pepperweed	Lepidium Latifolium	A	Perennial, 1 to 3 feet in height; leaves lanceolate, bright green to gray-green, entire to toothed, basal leaves larger than upper leaves; inflorescence a raceme. Flowers are white, in dense clusters near ends of branches, very small; fruit a silicle; seeds 2 per fruit, rounded, flattened, slightly hairy, about 1/16 inch long, and reddish-brown. Deep-seated rootstocks make this weed difficult to control. Grows in waste places, wet areas, ditches, roadsides, and cropland. Flowering occurs from early summer to fall.
	Poison Hemlock	Conium Maculatum	B	A biennial native to Europe that grows 6 to 8 feet tall. Stems are erect, stout and purple-green, finely pinnately divided three or four time and leaflets are segmented and 1/8 to 1/4 inch long. Lower leaves on long stalks clasp the stem. Stems are covered with purple spots at all growth stages. All parts of plant are poisonous including the large white taproot. Humans have been poisoned by mistaking the plant for parsley.
	Poverty Sumpweed	Iva Axillaris	C	A perennial, 6 to 18 inches tall. Stems are erect, much branched, smooth or slightly hairy. Leaves are mainly opposite, numerous, sessile, entire, narrowly oblong, 1/4 to 3/4 inch long, rough-hairy, harsh and stiff to touch. The small tubular flowers are borne in small heads which hang from the axils of the upper leaves; achenes are deep gray to almost black, wedge-shaped, 1/8 inch long with a rough surface.
	Puncturevine (Goatheads)	Tribulus Terrestris	C	Puncturevine is annual, prostate or somewhat ascending, mat forming, with trailing stems, each 1/2 to 5 feet long. Leaves opposite, hairy, divided into 4 to 8 pairs of leaflets, each about 1/4 to 1/2 inch long and oval. Flowers are yellow, 1/3 to 1/2 inch wide with 5 petals, borne in the leaf axils. Fruits consist of 5 sections which, at maturity, break into tack-like structures with sharp, sometimes curving spines, each section 2 to 4 seeded. Flowering from July to October. Seed will remain dormant for 4 to 5 years, making eradication difficult.
	Purple Loosestrife	Lythrum Salicaria	A	A rhizomatous perennial with erect stems, often growing 6 to 8 feet tall, usually associated with moist or marshy sites. Leaves are simple, entire, and opposite or whorled. Rose-purple flowers having 5 to 7 petals are arranged in long vertical racemes. Purple loosetrife, is an introduced European ornamental species that often escapes to aquatic sites such as streambanks or shorelines of shallow ponds. Infestations can become dense and impede water flow in canals and ditches.
	Quackgrass	Agropyron Repens	C	An aggressive perennial grass reproducing by seed, or spreading by a shallow mass of long, slender, branching rhizomes. Rhizomes are usually yellowish-white, sharp pointed, somewhat fleshy. They are able to penetrate hard soils or even tubers and roots of other plants. Stems are erect and usually 1 to 3 feet tall. Leaf blades are 1/4 to 1/2 inch wide, flat, pointed and have small auricles (ear like appendages) at the junction of blade and sheath. Because of the ability of broken rhizome segments to grow and produce new plants, it is extremely difficult to control mechanically.
	Rush Skeletonweed	Chondrilla Juncea	A	Perennial, 1 to 4 feet tall. Starting at the stem base for 4 to 6 inches, stems usually have downwardly bent coarse hairs; smooth stems above. Leaves form in a basal rosette, sharply toothed, and wither as the flower stem develops. Leaves of the stem are inconspicuous, narrow and entire. Flowering heads are scattered on branches, approximately 3/4 inch in diameter, with 7 to 15 yellow, strap-shaped flowers. Seeds are pale brown to nearly black, about 1/8 inch long. Flowering and seed production occur from mid-July through frost.
	Russian Knapweed	Centaurea Repens	A	Perennial, forming dense colonies by adventitious shoots from widely spreading black roots. Stems are erect, openly branched, 18 to 36 inches tall. Lower leaves are deeply lobed, 2 to 4 inches long; upper leaves entire or serrate, narrow to a sessile base. Cone-shaped flowering heads are 1/4 to 1/2 inch in diameter, solitary at the tip of leafy branchlets. Flowers are pink to lavender. Many pearly involucral bracts form with rounded or acute papery margins. Forms colonies in cultivated fields, orchards, pastures and roadsides. Flower occurs from June to September.
	Russian Thistle	Salsola Iberica	B	A rounded, bushy, much branched annual, 1/2 to 3 feet tall, reproducing by seed. Stems are usually red or purple striped. Leaves are alternate; the first are long, string-like and soft, with later leaves short, scale-like and tipped with a stiff spine. Seeds are spread as mature plants break off at ground level and are scattered by the wind as tumbleweeds. Seedling plants have long, fleshy leaves; herbicide applications should be made at this growth stage.
	Scotch Broom	Cytisus Scoparius	B	A woody shrub, up to 10 feet tall with many more-or-less erect branches that are angled and dark green. Leaves are mostly 3-parted with entire leaflets. Flowers are showy, yellow and abundant. Pods are flattened, brown or black, with white hair on the margins. This aggressive shrub is a problem in pastures, forests and wasteland. The pods at maturity can split noisily, ejecting the seeds some distance from the plant.
	Scotch Thistle	Onopordum Acanthium	A	Biennial that grows up to 12 feet tall. Stems have broad, spiny wings. Leaves are large, spiny, and covered with fine dense hair, giving a grayish appearance. Upper leaves are alternated, coarsely lobed; basal leaves may be up to 2 feet long and 1 foot wide. Flower heads are numerous, 1 to 2 inches in diameter, bracts spine-tipped. Flowers are violet to reddish. Fruits are about 3/16 inch long, tipped with slender bristles. An aggressive plant that may form stands so dense that they are impenetrable to livestock. Best controlled in the rosette stage.
	South American Waterweed	Elodea Densa	C	Rooted; stems many-branched. Dark to bright green leaves usually twice as long as wide (3/4'' long and 1/3'' wide) with finely toothed margins. Very tightly packed leaves towards the stem tips, leaves usually in whorls of fours American waterweed lives entirely underwater with the exception of small white flowers which bloom at the surface and are attached to the plant by delicate stalks. It produces winter buds from the stem tips which overwinter on the lake bottom. It also often overwinters as an evergreen plant in mild climates. In the fall leafy stalks will detach from the parent plant, float away, root, and start new plants. This is American waterweed's most important method of spreading, with seed production playing a relatively minor role.
	Spiny Cocklebur	Xanthium Spinosum	C	Annual with spreading or erect stems, up to 2 feet long. Leaves are densely covered below with short white hairs and white-veined above, blades 1 to 3 inches long, narrow, generally with 2 short basal lobes or teeth, and a stiff 3 forked spine at the junction with the stem.
	Spotted Knapweed	Centaurea Maculosa	B	Biennial or usually short-lived perennial with a stout taproot. It can have one or more stems, branched 1 to 3 feet tall. Basal leaves up to 6 inches long, blades narrowly elliptic to oblanceolate, entire to pinnately parted; principal stem leaves pinnately divided. Flowering heads are solitary at end of branches; involucral bracts stiff and tipped with a dark comblike fringe. The ray flowers are pinkish-purple or rarely cream colored. Fruits are bout 1/8 inch long, tipped with a tuft of persistent bristles. There is some evidence that knapweeds release chemical substances which inhibit surrounding vegetation. The flowering period is from June to October.
	Squarrose Knapweed	Centaurea Virgata	A	A long-lived taprooted perennial typically reaching heights of 12 to 18 inches. Stems are highly branched, with deeply dissected lower leaves and bract-like upper leaves. Flower heads are relatively small, containing 4 to 8 rose or pink colored flowers, usually developing no more than 3 to 4 seeds per head. Bract tips are recurved or spreading, with terminal spine longer than lateral spines on each bract. Seed heads are highly deciduous, falling off the stems soon after seeds mature.
	St. Johnswort	Hypericum Perforatum	C	The roots of this plant are an abbreviated taproot system. The roots branch deeply into the earth, however some of them do not and are shallow, these are usually the ones that reproduce. This plant has numerous erect stems, that appear rust colored. The stems are also woody and grow anywhere from 30-120 cm tall, (2-5ft). The leaves of this plant are oblong and/or elliptic, they contain transparent glands, which produce an oil that makes animals photosensitive. These leaves are attached directly to the stem and the edges of the leaves contain tiny black dots.
	Sulfur Cinquefoil	Potentilla Recta	A	Perennial 1 to 1 1/2 feet tall, with well developed root stocks. Leaves palmately compound with 5 or 7 toothed leaflets on each leaf. Leaves that are sparsely hairy appear green on the underside. Flowers light yellow with 5 petals, each flower producing numerous single-seeded oval achenes. Often found in disturbed areas such as roadsides and pastures. Flowering occurs from May to July.
	Tamarix	Tamarix Ramosissma	A	Deciduous or evergreen shrubs or small trees, 5 to 20 feet tall. Bark on saplings and stems is reddish-brown. Leaves are small and scale-like, on highly branched slender stems. Flowers are pink to white, 5 petalled.
	Tansy Ragwort	Senecio Jacobaea	A	Biennial or short-lived perennial from a taproot. Stems are 1 to 6 feet tall, solitary or several, simple up to the inflorescence. Leaves 2 to 8 inches long, alternate and equally distributed, mostly 2 to 3 times pinnately lobed, the terminal lobe generally larger than the lateral ones. Flowering heads are numerous. Both ray and disk flowers are yellow; ray flowers are 1 to 13 in number and 1/4 to 1/2 inch long. Flowering occurs from July to September. Toxic to cattle and horses.
	Western Water Hemlock	Cicuta Maculata	C	Water hemlock has small, white flowers that grow in umbrella like clusters. Side veins of the leaves lead to notches, not to tips at the outer margin. The thick rootstalk of water hemlock contains a number of small chambers. These hold a highly poisonous brown or straw-colored liquid that is released when the stem is broken or cut. Thick, fleshy tubers and slender individual roots grow from the bottom of the rootstalk. Water hemlock grows in wet seepage areas of meadows, pastures, and in streams. It reaches a height of 0.5 to 1.0 meters. The plant is a perennial in the carrot family. Water hemlock is the most violently toxic plant that grows in North America. Only a small amount of the toxic substance in the plant is needed to produce poisoning in livestock or in humans.
	Whitetop	Cardaria Spp.	A	A deep rooted perennial up to 2 feet tall, reproducing from root segments and seeds. Leaves are blue-green in color, lance-shaped. Lower leaves are stalked; upper leaves have two lobes clasping the stem. Plants have many white flowers with four petals, giving the plant a white, flat-topped appearance. Heart-shaped seed capsules contain two reddish-brown seed separated by a narrow partition. Plants emerge in early spring and have bloomed by mid summer. Can be controlled by herbicides.
	Yellow Flag Iris	Iris Pseudacorus	B	Big, vigorous plant bearing beard-less bright yellow flowers above thick, slightly bluish foliage. Individual flowers have delicate, reddish-brown markings against the yellow color.
	Yellow Toadflax	Linaria Vulgaris	B	Perennial, 1 to 2 feet tall, reproducing by seed and underground rootstocks. Leaves are pale green, numerous, narrow, pointed at both ends, 2 1/2 or more inches long . Flowers are 1 inch long with a bearded, orange throat. Fruit is round, 1/4 inch in diameter, brown, 2-celled, with many seeds. Seeds are dark brown to black, 1/12 inch in diameter, flattened with a papery circular wing. This creeping perennial is an aggressive invader of rangelands, displacing desirable grasses.