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Weed Guide

This guide initially displays all weeds in the Los Alamos area classified in NM as noxious regardless of shape. Use the selectors below to include nonclassified weeds or select a specific set, either by shape or name.

The term weed is commonly used to denote a plant that is growing in an area where it is not valued. It is officially defined by the USDA Animal and Plant Health Inspection Service as being any plant that poses a threat to agriculture and/or a natural ecosystem. A noxious weed is one that is particularly troublesome and can directly or indirectly injure or cause damage to crops, livestock, or natural resources.

In general, plants that are within their native range live in balance with their environment and are not typically considered to be weeds. Issues can occur, however, if a plant is introduced, either directly or indirectly, to a new ecosystem. These, now non-native plants, may be able to thrive in their new environment. If so, these naturalized plants can fall into one or two categories long term: (1) plants that are valued for their flowers and fruit and (2) plants that are rapidly considered to be weeds. The plants in the latter category are those that are generally regarded as noxious weeds.

While some species shown here are included in the PEEC Flower and Tree Guides, this guide concentrates on some of the nastier introduced species that you might see in your yard or on local trails. In addition, this guide includes some native plants that meet the general definition of weed.

Weed References

A Plan For the Control of Invasive Species on Los Alamos County Open Space — Craig Martin [PDF]
Los Alamos Master Garden Weed List
NMSU Weed Information
SEINet: Southwest Biodiversity
Some Common Lawn and Garden Weeds of Los Alamos, NM — Dorothy Hoard and Teralene Foxx [PDF]
Troublesome Weeds of NM
USDA: Introduced, Invasive, and Noxious Plants
Weed Alert
Weeds of the Los Alamos Area — Teralene Foxx [PDF]

Subject Area Experts (all guides)

Steve Cary (butterflies)
Beth Cortright (insects)
Terry Foxx (invasive plants)
Leslie Hansen (mammals)
Richard Hansen (fish, mammals)
Dorothy Hoard (butterflies, trees)
Chick Keller (flowers, herbarium)
Shari Kelley (geology)
Kirt Kempter (geology)
Garth Tietjen (reptiles)
David Yeamans (birds)

Web Development and Content Management

Pat Bacha
Jennifer Macke
Graham Mark
Akkana Peck


Please contact us for local nature questions and sightings. We welcome comments, corrections, and additions to our guides.

For more information about local nature, please visit our Nature Blog or subscribe to PEEC This Week.

Make Selection
Russian Thistle, Prickly Russian Thistle, Russian-thistle, Tumbleweed

Family: Amaranthaceae (Amaranths)
Size: up to 40 in (102 cm)
Growth: forb/herb; annual

Status: non-native; classified weed (common)
Native Range: Africa, Asia, and Europe
NM Noxious Weed Class: C – widespread

Habitat: rangeland, croplands, roadsides, industrial areas, and along railroad right-of-ways
Typical location: White Rock

Control Notes: pull up just below ground level before seeds set; repeated mowing or tilling effective; control with leaf mining moth poor; several herbicides effective

Salsola tragus arrived in North America in the late 1800’s. Since then it has become one of the most troublesome weed in the drier parts of the western states. It not only infects ranges, pastures and cropland but is the is the host for the beet leafhopper which is the vector for a virus infecting a number of food crops such as tomatoes, beans, and melons. Lastly, mature plants that die out, break off, and tumble away present a potential hazard as they blow across roads, startling motorists, and fill irrigation ditches, blocking water flow to crops.

Russian Thistle is a bushy, spiny plant with upward-curving branches and stiff, prickly leaves. The plant looks bluish-green overall and has a deep taproot with spreading lateral roots capable of extracting moisture deep within the soil. The flowers are small and mostly solitary and located in the leaf axils. They are brownish to pinkish red. Seeds are dispersed by the tumbleweeds as they are tossed around by the wind.

Young plants can be used as fodder and is palatable to a variety of wildlife species. It is a particular favorite of prairie dogs. Young shoots have even been cooked and eaten by humans. The seeds are consumed by several different birds and small mammals. Lastly, the plants have been used since antiquity to aid in the produce a concentrated solution of sodium carbonate that is added to other ingredients for making soap and glass.

Russian Knapweed, Hardheads, Truestan Thistle

ACRE3 (Acroptilon repens, Rhaponticum repens)

Family: Asteraceae (Daisies)
Size: up to 36 in (91 cm)
Growth: forb/herb; perennial

Status: non-native; classified weed (common)
Native Range: Eurasia
NM Noxious Weed Class: B – limited distribution

Habitat: disturbed areas, roadsides, pastures, waste places, and croplands
Typical location: Anniversary Trail

Control Notes: can resprout from root fragments so mechanical methods in general not highly effective, though repeated cutting/pulling can control but not eliminate an infestation; fire and biological controls not very effective; herbicides should be used as last resort and applied before seeds produced

Russian Knapweed was accidentally introduced into North America in the early 1900’s as a seed contaminant. It spreads rapidly, crowding out other species and reducing the quality of crop (alfalfa, wheat, barley, and oats) and range lands. Though it is found throughout most of the US, the area west of the Rocky Mountains is the most highly infected. This species can cause chewing disease in horses.

The stems of Russian Knapweed grow out from from a basal rosette of leaves. The leaves, themselves, are long and lobed at the bottom of the plant and become smaller and less lobed towards the top. The urn-shaped flowers are pink to purple and become straw-colored when mature. Fruits consist of white capsules with tufts of hair. The plant has deep roots and can live up to 75 years or more.

Russian Knapweed is toxic to horses causing something known as chewing disease. However, most livestock avoid the plant due to its bitter taste. There have been some studies uses extracts of the plant as an insecticide.

Skeletonleaf Bur Ragweed, Skeletonleaf Bursage, Burragweed

Family: Asteraceae (Daisies)
Size: up to 36 in (91 cm)
Growth: forb/herb; perennial

Status: native; classified weed (common)
Native Range: west-central United States
NM Noxious Weed Class: B – limited distribution

Habitat: disturbed sites such cultivated fields, pastures, and waste areas

Control Notes: mowing does not kill bursage but may delay seed production; number of herbicides are effective

Despite being a native plant, Skeletonleaf Bur Ragweed is a particularly aggressive weed. It emerges earlier than crops in which it may be associated, thus outcompeting them for light, moisture, and nutrients. In addition, livestock find it unpalatable. The plant is considered to be unsightly while its pollen aggravates the allergies of those individuals with ragweed sensitivity

Skeletonleaf Bur Ragweed has long, greenish-gray leaves that are deeply lobed with toothed edges. The lower leaf surface is white and covered with short, dense hairs. Each flower head contains either male or female flowers but not both. The flowers are rather inconspicuous and yellow in color and tend to droop. The fruits develop into light brown burs with numerous short spines. Skeletonleaf Bur Ragweed is long lived and its extensive root system makes eradication very difficult. It does not appear to have any reported know uses.

Photo: Mary Carol Williams

Musk Thistle, Nodding Thistle, Nodding Plumeless Thistle

Family: Asteraceae (Daisies)
Size: up to 72 in (183 cm)
Growth: forb/herb; biennial, perennial

Status: non-native; classified weed (common)
Native Range: Europe and Asia
NM Noxious Weed Class: A – very limited distribution

Habitat: grasslands, disturbed areas, and agricultural settings

Control Notes: cut the plants down just as the flowers begin to open; dig up the plants and roots; musk thistle weevil can be introduced; lastly selective herbicides can be applied after the seedlings have emerged

Musk Thistle was accidentally introduced in the US in the early 1900s. Once established in area, it spreads rapidly due to the fact that a single plant can produce up to 120,000 seeds. Also the plant is difficult to control since the seeds can remain viable in the soil for over ten years. It is relatively unpalatable to livestock so Musk Thistle is a particular problem in pastures.

Carduus nuts is very tall and looks like it has stems and leaves that give it the appearance of spiny wings. The flower heads are red to purple and are made up of hundreds individual flowers. They are slowly, solitary, and hemispherical. The common name of Nodding Thistle is derived from the tendency of the flower heads to droop when mature. The seeds are straw-colored and have long bristles.

The flowers are a good source of food for hummingbirds and bees. Some birds, including the goldfinch, will eat the seeds. The plant can be eaten if the stalk is peeled. Young leaves can be made into a drink. Lastly, a tonic made from the seeds and leaves can be used to stimulate liver function.

Spotted Knapweed

CESTM (Centaurea stoebe, Centaurea biebersteinii, Centaurea maculosa)

Family: Asteraceae (Daisies)
Size: up to 36 in (91 cm)
Growth: forb/herb; biennial, perennial

Status: non-native; classified weed (common)
Native Range: Europe
NM Noxious Weed Class: A – very limited distribution

Habitat: along roadsides and railroads, pastures and abandoned fields, and vacant lots

Control Notes: mechanical removal before seed dispersal must eliminate at least 3 to 4 in (7 to 10 cm) of root crown; herbicides are effective; fire is not

Spotted Knapweed was most likely introduced into the US in the late 1800s through contaminated seed or ballast. The plant spreads aggressively, particularly in dryer regions, and crowds out both native species and forage plants. It is a nuisance and a potential hazard to animals and humans as the stems are stiff and scratchy. Once established areas of Spotted Knapweed can persist almost indefinitely. Once the plant matures and dries out, it breaks off at the base and then is blown around with the wind as a tumbleweed, dispersing seeds far and wide.

Spotted Knapweed is a short-lived plant with ribbed stems and a woody texture. The leaves are lobed and grayish-green with small bristly hairs. The flower heads are thistle-like with ray florets that are pink to purple. Typically there are 25 to 100 flower heads per plant. The seed heads are brown, finely haired, and elliptical in shape. There is a short tuft of white hairs at the tip of each seed.

Various long-tongued bees and butterflies will take nectar from the Spotted Knapweed. It is also possible that some small rodents and birds will eat the seeds. Mammalian herbivores tend to avoid the plant due to its bitter foliage.

Canada Thistle, Creeping Thistle, Canadian Thistle

Family: Asteraceae (Daisies)
Size: up to 40 in (102 cm)
Growth: forb/herb; perennial

Status: non-native; classified weed (common)
Native Range: Eurasia
NM Noxious Weed Class: A – very limited distribution

Habitat: dry to moist open areas including fields, grasslands, pastures, stream banks, and open forests

Control Notes: late spring burns are effective but must be done 3 years in a row; pulling can stimulate the plants unless done repetitively; mowing needs to be done during the early bud stage

Canada Thistle was accidentally introduced to North America in the 1600s and is now designated as a noxious weed in 43 states. Despite the common name it does not have a Canadian origin. The plant can form dense stands that displace native plants disrupting the plant community structure. Once established it is very difficult to remove.

The plant has lance-shaped leaves with clusters of purple or pink flowers borne at the end of the stems. It produces numerous short seeds that are dispersed by wind. Canada Thistle can also spread by roots. It has an extensive underground structure with four types — (1) thick, horizontal roots, (2) long, vertical roots, (3), short, fine shoots, and (4) underground vertical stems. The plant is capable for forming extensive colonies from the numerous underground shoots and is often the first plant to invade a disturbed area. It thrives in moderate sunshine and temperatures with plentiful water.

The plant is actually more nutritious than alfalfa but livestock avoid the plant because of its spines, though they will sometime eat the flowers. Sheep and goats will only eat the very young plants. However, it is very beneficial to pollinators that rely on nectar.

Bull Thistle, Spear Thistle, Common Thistle

Family: Asteraceae (Dasies)
Size: 40 – 68 in (102 – 173 cm)
Growth: forb/herb; biennial

Status: non-native; classified weed (common)
Native Range: Europe, western Asia, and northwestern Africa
NM Noxious Weed Class: B – limited distribution

Habitat: colonizes bare, disturbed ground, and persists in heavily grazed grasslands

Control Notes: best way to clear is by deep cutting the taproot before the seeds mature; use a post-emergence herbicide when it is in the rosette to flower stage

Bull Thistle and the very similar Canada Thistle (C. arvense) are easily confused with native New Mexico Thistle (C. neomexicanum) which does not spread aggressively. The trick is to look for prickles on the stems.

Invasive thistles have spiny stems while native New Mexico Thistle does not.

The plant blooms from June through October. The flowers are dark pink to purple with spiney bracts and elongated stems. The flowers have a large amount of nectar for pollinators. The seeds are dispersed by the wind and eaten by many small birds. However, while sheep and goats will gaze on Bull Thistle, cattle will not eat it. The plant is only spread by seed which can persist in the soil for up to 4 years.

Jointed Goatgrass, Jointgrass

AECY (Aegilops cylindrica)

Family: Poaceae (True grasses)
Size: 6 – 20 in (15 – 51 cm)
Growth: graminoid; annual

Status: non-native; classified weed (common)
Native Range: southern Europe
NM Noxious Weed Class: C – widespread

Habitat: disturbed soil, along roadways, and field edges

Control Notes: use multiple strategies (tilling and mowing, prescribed fire, and herbicides) to eliminate live plants and prevent seed formation including checking seed stock for the presence of weeds

Jointed Goatgrass was introduced into North America at several different times and locations. It was most likely brought in with contaminated winter wheat during the late 1800s. Currently about 2 million hectares are infected in the US with an annual increase of 20,000 hectares per year. It is primarily spread by human activity such as planting contaminated wheat, transporting contaminated machinery to different fields, and using particular types of farm machinery that result in greater spread of the seeds as well as creating soil conditions favored by Jointed Goatgrass.

Jointed Goatgrass and winter wheat are genetically linked and potentially able to cross-breed. The shape and size of their seeds are similar making it very difficult to clean up grain supplies. The two plants even germinate at the same time and grow at the same rate. Both produce erect flowering stalks with spikelets containing seeds. When mature the Jointed Goatgrass spikelets break into individual segments and can be mistaken for winter wheat straw.

As unexpected as it might seem, Jointed Goatgrass has been used with winter wheat to improve its tolerance to a variety of stresses, including diseases and insects. Also cattle in some areas are able to graze on it; while it can be ground into feed for other animals.

Cheatgrass, Drooping Brome, Cheat Grass

Family: Poaceae (True grasses)
Size: 6 – 24 in (15 – 61 cm)
Growth: graminoid; annual

Status: non-native; classified weed (common)
Native Range: Europe, southwestern Asia, and northern Africa
NM Noxious Weed Class: C – widespread

Habitat: grows well in coarse-textured soils as well as eroded areas and areas low in nitrogen; pinon-juniper and scrubland

Control Notes: mowing within a week of flowering will reduce seed dispersal; burning before seed dispersal will kill the seeds but leaves the site vulnerable to re-infestation; variety of herbicides effective

Cheatgrass is a winter annual with smooth stems and hairy leaves. The flowers of this plant are arranged on multi-branched spikes with bristles. The flowers do not open and are self-pollinating. Cheatgrass is most recognizable by it droopy seed heads, leading to the common name of Drooping Brome.

The plant often enters a site through disturbed ground, and then quickly expands into surrounding areas through its rapid growth and prolific seed production. The seeds ripen in late spring to early summer and are dispersed by wind, small rodents, and as a contaminant in hay and other grain. Many kinds of livestock as well as deer, small mammals, and game birds will feed on Cheatgrass.

Common Mallow, Cheeseweed, Cheeseplant, Buttonweed

Family: Malvaceae (Mallows)
Size: up to 24 in (61 cm)
Growth: forb/herb; annual, perennial

Status: non-native; classified weed (common)
Native Range: Eurasia
NM Noxious Weed Class: not classified

Habitat: disturbed soil in cropland, abandoned fields, farm lots, vacant lots, areas along roads, edges of yards, and gardens

Control Notes: hand pull small areas before the seeds form; mature plants very resistant to most herbicides so the best way to control is cover area with healthy plants

The Common Mallow is one of several species of mallow introduced into North America from Europe that have become naturalized throughout most of the the US and Canada. The deep taproot of these plants makes them particularly difficult to get rid of and has earned them the classification of “invasive” in numerous areas, particular in the eastern portion of the US.

The Common Mallow has rounded fuzzy gray-green leaves and showy light pink or purple blossoms with a notch at the tip of each petal. The seeds of this plant have a very thick coat which allows them to survive in the soil for long periods of time. The plant has been called Cheeseweed due to the facts that the seed pod is round and flat with divisions like a wheel of cheese.

Common Mallow is in the Malvaceae family which includes plants such as cotton, hibiscus, and okra. All parts of the plant are edible: leaves and flowers can be eaten in a salad and dried leaves can made into a tea.

Common Purslane, Verdolagas, Little Hogweed, Red Root, Pigweed

POOL (Portulaca oleracea)

Family: Portulacaceae (Purslane)
Size: up to 16 in (41 cm)
Growth: forb/herb; annual

Status: uncertain; classified weed (common)
Native Range: Africa, Europe, Middle East, India, Australasia, and North America?
NM Noxious Weed Class: B – limited distribution

Habitat: highly disturbed soil; rocky bluffs, cropland, gardens, barnyards, cracks in city sidewalks, and pavement

Control Notes: aggressive treatment is not necessary as disturbed areas will eventually be restored with native ground cover; a post-emergence broadleaf herbicide when the plant is a seedling works

The status of Common Purslane with respect to being native or non-native is uncertain. While the plant can be found in growing in many parts of the world, there is no record of its introduction into North America. In contrast, there is some evidence that it was in the continent since at least pre-Columbian times when Native Americans who ate the plant may have spread its seeds.

Common Purslane has smooth, reddish stems and leaves that are clustered at stem joints and ends. The flowers are solitary and yellow in color. The plant spreads by seeds and by stem fragments. The stems branch out from a central point, forming a mat up to 1 ft (0.3 m) across. Multiple, close-packed plants can form a dense ground cover. The plant is not considered invasive in the local area but it can outcompete native plants.

There are cultivated forms of Purslane that are grown for the fleshy stems and leaves. It can be used raw in a salad or cooked in a soup or stew. The leaves are often sold in farmers’ markets. Small mammals will eat the seeds while herbivores will forage on the foliage.

Dalmatian Toadflax, Balkan Toadflax, Broadleaf Toadflax

Family: Scrophulariaceae (Figworts)
Size: up to 36 in (91 cm)
Growth: forb/herb; perennial

Status: non-native; classified weed (common)
Native Range: Mediterranean area
NM Noxious Weed Class: A – very limited distribution

Habitat: fields, overgrazed pastures, rangeland, waste areas, and along roadsides

Control Notes: pull up small infestations, however, the roots tend to beak off and new shoots will re-sprout; fire and mowing are not effective; some herbicides can be used; best thing is to maintain a healthy native plant community

Dalmatian Toadflax was introduced into North America in the lat 1800s as an ornamental flowering plant. Since then, it has escaped the garden and spread to the majority of US states and most of the Canadian provinces. It is responsible for significantly reducing livestock production on affected land by crowding out valuable forage. It has no value as food and may actually be harmful to livestock, though most animals avoid it.

The overall form of the Dalmatian Toadflax is narrow and upright with multiple stems growing from a single woody base. The leaves are blue-green and egg- or heart-shaped. Bright yellow flowers grow on a spike on the upper stems. The flowers are five-lobed with a bit of orange or white fuzzy beard. The plant has fast-growing lateral roots that can extend up to 10 ft (3 m) or more. A mature plant may produced up to 500,000 seeds.

Dalmatian Toadflax is a cousin to the Common Toadflax which is shorter with smaller flowers and narrow, linear leaves. Like the Common Toadflax, the Dalmatian Toadflax has been used as a fabric dye and in a tea for medicinal purposes.

Common Toadflax, Yellow Toadflax, Butter and Eggs, Jacob’s Ladder, Wild Snapdragon

Family: Scrophulariaceae (Figworts)
Size: up to 24 in (61 cm)
Growth: forb/herb; perennial

Status: non-native; classified weed (common)
Native Range: Eurasia
NM Noxious Weed Class: A – very limited distribution

Habitat: roadsides, edges of fields, rangelands, meadows, cultivated fields, and wastelands

Control Notes: digging up infested areas several times during a season beginning in spring eliminates most of the plant; seeding with well adapted grasses can outcompete the plant; also certain insects that can be introduced that will feed on the plant.

Common Toadflax was brought to North America by immigrants that cultivated for use as a yellow dye. It is thought to have escape to the wild in the mid-1800’s. The plant can reproduce by seed and creeping roots; thereby often forming colonies.

Common Toadflax has very narrow, hairless leaves with pointed tips on relatively unbranched stems. It produces yellow flowers with orange throats and a spur-like appendage at the base. Seeds are dark in color, flattened, and have a papery wing. They can remain viable for up to 10 years in the soil. The plant is similar in appearance to the Dalmatian Toadflax. The latter has more heart-shaped leaves, slightly larger flowers, and is taller overall.

Common Toadflax has diuretic and fever-reducing properties. A tea made from the leaves is drunk to treat a wide variety of diseases. In addition, the leaves have been made into an ointment for the skin diseases. It should be noted that the plant may be mildly toxic to livestock.

Herb Sophia, Fluxweed, Flixweed Tansymustard

Family: Brassicaceae (Mustards)
Size: 10 – 30 in (25 – 76 cm)
Growth: forb/herb; annual, biennial

Status: non-native; classified weed (common)
Native Range: Europe and northern Africa
NM Noxious Weed Class: C – widespread

Habitat: disturbed sites, washes, roadsides, railroad rights-of-way, and old fields

Control Notes: maintaining a healthy plant community in favor of late successional plants is the best way to prevent its establishment; if necessary, mechanical removal or herbicides are effective

Herb Sophia is a late successional plant that invades rangelands disturbed by heavy grazing. It is also a common invasive plant during restoration projects. It is considered a crop pest as it potentially contributes to the transmission of some plant viruses. Large quantities of the plant are toxic to livestock, causing blindness and staggering. Along the same lines, most wildlife do not appear to consume Sophia Herb, but rather favor other tansy mustards, though it is a favored food for some butterfly larva.

Herb Sophia is one of the first plants to appear in spring. A rosette of basal leaves form first, from which sprout a stem and additional leaves. Flowers appear at the tips of branching stems as flat clusters. Multiple seeds form in inch long pods.

In German, the plant is call Sophienkraut in honor of Saint Sophia who protects against late frost. In India, the stems and leaves are used as a fiber. In Iran, the seeds are used to favor a cold drink during the summer. The seeds have also been used as a spice, similar to pepper. Lastly, Herb Sophia has been used medicinally to treat dysentery as well as a variety of other used.

Hoary Cress, Globed-podded Hoarycress, Heart-podded Hoarycress, Whitlow Grass, Whitetop

CADR (Lepidium draba, Cardaria draba)

Family: Brassicaceae (Mustards)
Size: up to 24 in (61 cm)
Growth: forb/herb; perennial

Status: non-native; classified weed (common)
Native Range: southeastern Europe and western Asia
NM Noxious Weed Class: A – very limited distribution

Habitat: grainfields, hayfields, and on roadsides

Control Notes: pull or mow removing roots, if possible, and monitored for regrowth from root fragments; mowing can reduce seed production and better enable targeting of herbicides; plowing once a month for several years will eliminate the plant

Hoary Cress was most likely introduced into North America in contaminated shipments of alfalfa. It was found first in California in 1876. It is an aggressive plant crowding out native species and reducing crop yields. A single plant can grow to cover an area up to 12 ft (3.7 m) in its first year. It can then spread at a rate of up to 5 ft (1.5 m) per year. Its roots may go down as far as 15 ft (4.5 m).

Hoary Cress stems are branched and covered with light-colored soft hairs. The leaves are mostly toothed. The flower heads are slightly domed clusters with individual white, clawed flowers . The many, small flowers give the plant its white-topped appearance. Lepidium draba seed pods are heart-shaped and thus differ from the other whitetop species. The plant reproduces both by seeds and rhizomes.

The leaves of Hoary Cress can be eaten early in the spring. They have a spicy mustard flavor. However, as the plant matures, the taste become bitter and unpalatable while the nutritional value to livestock decreases.

Broadleaved Pepperweed, Perennial Pepperweed, Peppergrass, Tall Whitetop

LELA2 (Lepidium latifolium)

Family: Brassicaceae (Mustards)
Size: 36 – 48 in (91 – 122 cm)
Growth: forb/herb; perennial

Status: non-native; classified weed (common)
Native Range: southern Europe, northern parts of Africa, and southwestern Asia
NM Noxious Weed Class: A – very limited distribution

Habitat: most invasive in wetlands, but from there can spread to the riparian zone, and further to rangelands roadsides

Control Notes: seedlings can be pulled up but not a long term control method; burning not effective; mowing followed by herbicide has been an effective

Broadleaved Pepperweed was accidentally introduced into the United States around 1936 as a contaminant in seed. It has spread rapidly and can form dense monocultures that crowd out native species.

The plant has numerous woody stems and waxy leaves with clusters of small, white flowers and small, two-seeded red fruits. The seeds lack a hard coat, leading to the belief that seed viability may be short. The root network is extensive and can reach as deep as 9 ft (3 m).

The dried stems of the plant are sometimes used in floral arrangements. Leaves, shoots, and fruits are edible. The bitter taste of the plant can be removed by boiling the shoots and leaves, and then soaking in water for a few days. Cattle, sheep, and goats will graze on Broadleaved Pepperweed, especially on the rosettes in early spring.

Russian Olive, Russian Silverberry

ELAN (Elaeagnus angustifolia)

Family: Elaeagnaceae (Oleasters)
Size: 180 – 276 in (457 – 701 cm)
Growth: shrub, tree; perennial

Status: non-native; classified weed (common)
Native Range: Eurasia
NM Noxious Weed Class: C – widespread

Habitat: canyon, disturbed soil, grassland, riparian, and scrubland

Control Notes: mow saplings; use cut stump method for mature trees — cut as low as possible, apply high-strength vinegar or herbicide

The Russian Olive was imported into North America by the late 19th century. It is a fast-growing, resilient and drought-tolerant plant that could bed used to prevent erosion and provide wind-resistant hedges. Unfortunately, these same properties, lead to uncontrolled spreading and overcrowding of native vegetation. The plant is now listed on noxious weed lists in many parts of the US and Canada. In fact, in some areas, it is even mandatory to cut down and remove existing plants.

Elaeagnus angustifolia is similar in appearance to a true olive Olea europaea but not related. It looks like a thorny shrub or small tree. Stems, buds and leaves have a dense covering of silvery-to-rusty scales. Young branches are whitish, while the older branches are brown-to-black and tend to have thorns. Leaves are oblong with silver scales on both sides. Flowers are fragrant with silver on the outside and yellow within. There are usually one to three flowers grouped together. Each oblong fruit which is like a berry contains one seed and is covered by silver scales.

Russian Olives are grown in parts of their native range as an ornamental shrub. The flowers attract honey bees and the fruits are eaten by birds and other small animals. The fruits taste sweet but are usually dry and mealy. Lastly, the Russian Olive “olives” have been harvested for their oil since ancient times.

Saltcedar, Five-Stamen Tamarisk

TARA (Tamarix ramosissima)

Family: Tamaricaceae (Tamarisks)
Size: 40 – 280 in (102 – 711 cm)
Growth: shrub, tree; perennial

Status: non-native; classified weed (common)
Native Range: Eurasia
NM Noxious Weed Class: A – very limited distribution

Habitat: riverbanks, stream courses, and irrigation ditches

Control Notes: removal by hoeing or digging can be used for small areas; grubbing with a tractor and excavating individual trees effective; some biological controls under study; aerial spraying herbicides tested successfully

Tamarix famosissima is grown in its native range as an ornamental. It is very hardy and tolerates poor soils well. It was for these same reasons that Saltcedar was introduced into the US in the 1830’s where it was actively planted as a windbreak and for stream bank stabilization. Unfortunately, the plant spread rapidly, consuming large amounts of groundwater in riparian and wetland habitats and crowding out native species. It is now a noxious weed through the Southwest and drier areas of California.

Saltcedar is a shrub or small tree with bark that is reddish when young and turning brown with age. The leaves are gray-green and have an unusual feathery quality. The blooms are quite showy with clusters of pale pink to white five-petaled flowers. The fruit consists of capsules that each contain numerous tiny seeds which are dispersed by the wind. The plant’s common name comes from the fact that it is able to tolerate salt water by excreting salt through special glands in its leaves. It produces salt deposits which both kill other species and cause increased erosion.

Livestock will browse on Saltcedar but the plant has little nutritional value and is generally not preferred. Goats, though, can be used to help suppress re-sprouting in areas under control. On the positive side, Saltcedear provides nesting habitats for some birds, including the endangered Southwestern Willow Flycatcher.

Siberian Elm

Family: Ulmaceae (Elms)
Size: 600 – 840 in (1,524 – 2,134 cm)
Growth: shrub, tree; perennial

Status: non-native; classified weed (common)
Native Range: central Asia
NM Noxious Weed Class: C – widespread

Habitat: on disturbed ground and abandoned lots, along railroad tracks, near field windbreaks, and close to vacant buildings

Control Notes: pull/dig up seedlings and small trees; girdling can be effective for mature trees in late spring to mid-summer, otherwise herbicides are required

Ulmus pumila has been widely cultivated both in its native range and in a large number of places world wide for its rapid growth and drought tolerance. It is thought to have been introduced into the US in 1905. The trees were cultivated at the USDA Experimental Station in North Dakota. They flourished there and were subsequently selected by the USDA for planting in the aftermath of the Dustbowl. Unfortunately, the plant is quite invasive in cities and open areas and has been classified as invasive in a large number of states. Fortunately, it rarely invades mature forests.

The Siberian Elm is a small to medium-sized tree or a tall bushy shrub. The bark is dry gray and irregularly fissured. Leaves are elliptical and change from dark green to yellow in autumn. The green and brownish-red flowers are rather small. The fruit is flat, round, and paper like. Each fruit or samara contains a single seed. A impressive local example of a Siberian Elm can be seen in Santa Fe at the Palace of the Govenors.

The Siberian Elm is of interest to botanists due to its resistance to Dutch elm disease. This has lead to the development of several hybrids between Ulmus pumila and other elm species trying to create a tree with a more native appearance but strong resistance to Dutch elm disease. In addition, as the area is getting drier and hotter, researchers are beginning to think that the Siberian Elm may be value when the native trees starting to die off.

Myrtle Spurge, Donkeytail Spurge, Blue Spurge

EUMY2 (Euphorbia myrsinites)

Family: Euphorbiaceae (Spurges)
Size: up to 6 in (15 cm)
Growth: forb/herb; biennial, perennial

Status: non-native; classified weed (common)
Native Range: southern Europe and Asia Minor
NM Noxious Weed Class: on watch list

Habitat: fields, rangelands, gardens, disrupted areas, and roadsides

Control Notes: for small areas, plants can be pulled early in the season prior to seed formation (use gloves to avoid the sap); for large areas herbicides may be needed

Myrtle Spurge was imported to to be grown as an ornamental plant. It grows extremely well in hot, dry areas. It is an aggressive plant and escaped cultivation into the wild where it is known for crowding out native species. It has been classified as a noxious weed in some regions. For example, it is illegal in Colorado to grow Myrtle Spurge and landowners are required by law to eradicate it.

Myrtle Spurge is a short evergreen with a woody base and trailing stems. The blue-green leaves are thick and waxy. with a point at the tip. They are arranged in tight spirals around the stems. The greenish flowers are inconspicuous but surrounded by bright, showy, yellow bracts. The flowers are arranged in clusters. The fruit consists of a bluish-green seed pod containing several long seeds which can be projected up to 15 feet from the plant.

Myrtle Spurge has a caustic, milky sap that can cause significant eye and skin irritation including redness, swelling, and blisters. Children and pets are particularly susceptible. Precautions should be taken when handling the plants.

Common Teasel, Fuller’s Teasel

Family: Dipsacaceae (Teasels)
Size: 36 – 72 in (91 – 183 cm)
Growth: forb/herb; biennial

Status: non-native; classified weed (common)
Native Range: Eurasia
NM Noxious Weed Class: B – limited distribution

Habitat: disturbed soil in open, sunny areas, roadsides, creeks, fields, pastures, and gardens

Control Notes: mow flowering stems prior to seed production; dig up the plants when the population is small; plant cover crops will reduce the infestation; use herbicides should be on pre-flowering plants

The stem and leaves of the Common Teasel are prickly and the flowers are dark pink or purple and for a head on the end of the stem. The genus name is derived from the word for thirst and refers to the way leaves cup at the stem can hold water. It has been proposed that this deters sap-sucking insects from climbing the stem.

Common Teasel was introduced into North American during the 1700s. It was cultivated for use in textile processing as the heads can be used as a comb for processing wool. The seeds are important in winter as food for some birds. Teasel is occasionally grown as an ornamental, while the dried heads are used by florists.

When the plant invades an area, it will form a large monoculture, displacing other species. It is not considered to be toxic but has been used for medical purposes. So using it for livestock is not advised.

Common Mullein, Great Mullein, Flannel Plant, Velvet Plant

Family: Dipsacaceae (Teasels)
Size: up to 72 in (183 cm)
Growth: forb/herb; biennial

Status: non-native; classified weed (common)
Native Range: Eurasia
NM Noxious Weed Class: C – widespread

Habitat: well-lit, disturbed soils in sides of banks, meadows, roadsides, forest clearings, and pastures

Control Notes: hand pull and hoe following by planting native plants; plant resistant to contact herbicides due to its hairy nature; burning is ineffective

Common Mullein was first introduced into the United States in the mid-1700s by Virginia colonists and used to poison fish as the leaves and seeds of the plant contain a natural pesticide. In addition, the flowers have been used as a hair dye; while the leaves were made into candle wicks or put into shoes to insulate them. Common Mullein is not eaten by grazing animals due to the plant’s many tiny hairs irritating hairs.

During the first year of its growth, Common Mullein forms a large basal rosette with fuzzy leaves. In the second year, it produces a large, erect, wooly stalk that can grow up to 8 ft (2.5 m) tall with yellow flowers. The flowers have a honey-like scent that arrests pollinators. After flowering the plant usually dies, leaving a very large number of minute seeds that are scattered by the winds.

Diffuse Knapweed, White Knapweed

Family: Convolvulaceae (Bindweeds)
Size: 8 – 40 in (20 – 102 cm)
Growth: forb/herb; annual, perennial

Status: non-native; classified weed (common)
Native Range: eastern Mediterranean
NM Noxious Weed Class: A – very limited distribution

Habitat: disturbed areas in fallow land, ditches, rangelands, and roadsides

Control Notes: cut, dig, or burn; certain insect species can control knapweed; some herbicides, often in combination, may help

Diffuse Knapweed was first identified in the North America in 1907 in an alfalfa field in Washington state. Presumably the seeds were transported in an impure seed shipment. The plant has spread rapidly throughout much of the western United States and Canada. It has been reported that it is increasing its range at a rate of 18% annually. Diffuse Knapweed invasiveness decreases plant diversity and wildlife habitat while increasing soil erosion rates. The plant has little value as forage as its thistles can damage the mouth and digestive tract of animals, both wild and domestic, trying to feed on it.

The plant consists of a highly branched stem with a large taproot and a basal rosette of leaves. Both the stems and leaves are covered in short, dense hairs. White or pink flowers grow out of urn-shaped heads located at the tips of many branches. Seeds are dark brown and small without a bristle structure. A single flower can produce 1,200 seed. It should also be noted that if a plant is broken off at the base, it will act like a tumbleweed dispersing its seed as it is blown around.

Field Bindweed, Creeping Jenny, European Bindweed, Smallflowered Morning Glory

COAR4 (Convolvulus arvensis)

Family: Convolvulaceae (Bindweeds)
Size: 1 – 2 in (3 – 5 cm)
Growth: forb/herb; perennial

Status: non-native; classified weed (common)
Native Range: Eurasia
NM Noxious Weed Class: C – widespread

Habitat: cultivated fields, pastures, gardens, lawns, and roadsides

Control Notes: a combination of techniques is necessary to control the plant; pull up when young and roots are still small; dig deep enough to get all of the root of older plants; frequent tilling at the bloom stage is helpful; patches can be treated with herbicide in mid-summer before they seed; bindweed gall mite or the bindweed moth can be released

Field Bindweed, despite its pretty flower, is New Mexico’s worst weed. It is very difficult to eradicate once it is established. Seeds can sprout after remaining dormant in the soil for as long as 20 years. Due to the plant’s extensive root system, it outcompetes crops for moisture and nutrients leading to reduced yields.

Field Bindweed is a vine with stems that run along the ground or climb up any available object. The stems can be up to 6 ft (2 m) long and will form dense, tangled mats. The leaves of the Field Bindweed are lobed at the base and generally arrowhead-shaped. The flowers consist of five fused petals that for a trumpet-like tube. They are white or purplish-pink in color. An individual flower is only open for a single day. The seeds are very small and pear-shaped. The seeds hard coat allows it to remain viable in the stomachs of migrating animals up to 5 days, resulting in long range dispersal.


Pajarito Environmental Education Center
Los Alamos Nature Center
2600 Canyon Road
Los Alamos, New Mexico 87544
(505) 662-0460
[email protected]

Ecoogical Weed Management Book Published

Dr. Charles “Chuck” Mohler’s book has been released! Read about it in Craig Cramer’s news article on the Cornell Agriculture and Life Sciences website.

Toxicity Concerns For Forage After Frost

We received a timely update on potential toxicity concerns with certain forages after frost. For more information, please see Oregon State University’s article or this one from the University of Kentucky.

Fall Weed Seeds and Equipment Clean-Out Article

A new article by Lynn Sosnoskie of Cornell University was published in the Cornell Extension Field Crop News today.

Clean that second-hand machinery before using! Remember that all equipment can move weeds from one field to another, and plan appropriately.

Late postemergence herbicide options for soybeans

By: Mike Hunter, CCE-North Country Regional Ag Team

A very popular question has been “What can I spray on my soybeans to control large weeds that weren’t controlled earlier in the season?”. Let me start out by saying that if you have waist high weeds in your soybeans the damage is done and most, if not all, herbicide applications will be a form of “revenge spraying”. Spraying very tall weeds usually provides unsatisfactory weed control. If you still have some weeds that are 6 inches tall or less there is a better chance to control them.

Roundup or glyphosate can be applied through the R2 (full flowering) growth stage on Roundup Ready or glyphosate tolerant soybeans. Enlist One and Enlist Duo can also be applied throughout the R2 growth stage in Enlist or E3 soybeans. Once the soybeans have reached the R3 (beginning pod) growth stage these products are no longer an option.

If the soybeans are at R3 (a pod 3/16” long found at one of the first four uppermost nodes) Cobra, Resource and Basagran are the options that are left. Cobra can be applied through R6 (full seed) or 45 days before harvest, Resource 60 days before harvest and Basagran 30 days before harvest. These are all selective, contact broadleaf herbicides. Unfortunately, none of these are very good at controlling common lambsquarters.

If you have any additional questions about late season soybean weed control, contact your local Cornell Cooperative Extension office.

Organic Weed Management in Apples

Cornell University’s Greg Peck and Kate Brown discussed a four-year trial of organic weed management strategies during apple tree establishment with Growing Produce author Thomas Skernivitz. Read about their conversation and research in Growing Produce’s June edition.

New Penn State resource for spring weed control in grass hay and pastures

Pennsylvania State University’s Dwight Lingenfelter and emeritus professor Bill Curran have published an article on spring weed control in grass hay and pastures. They break down best management practices for winter annuals like mustard weeds and common chickweed (emerge in the fall and flower/set seed in the spring), summer annuals like pigweeds, common lambsquarters, and common ragweed (emerge in the spring and flower/set seed in the late summer or fall), and biennial weeds like common burdock and bull and musk thistle (take two years to complete their life cycle). Check out their advice for the best timing of your spring weed management practices.

Lesser celandine: Spring garden and lawn invader

We just received a question from Erie County on this frustrating invasive weed. Here in Ithaca this species is in full flower right now (mid-April 2021), and can be seen carpeting the banks of many streams.

Lesser celandine (Ficaria verna, once Ranunculus ficaria), also known as fig buttercup, is a common woodland, garden, and lawn weed that you may see on your farm or property. It is one of the earlier plants to flower in our area, and is an aggressive spreader. It has a perfect storm of flexible reproduction and vegetative spreading mechanisms; it self-pollinates, reproduces by spreading roots, produces underground tubers that create new plants, and also has aboveground ‘bulbils’ that also start new plants. It’s difficult to remove once established.

Lesser celandine plant. Photo by Caroline Marschner of Cornell University.

Leaves: Lesser celandine leaves are dark green, glossy, shape variable but largely kidney-shaped, with a reptilian-esque pattern on the underside of the leaf.

Mature Plant: The mature plant is low growing and ephemeral, emerging in the early spring, flowering in April in New York, and senescing by early summer. Roots produce tubers that separate easily from the parent plant to form new infestations. The plant also develops aboveground bulbils, which also produce new plants, and seeds from flowers.

Flowers/fruit: Flowers have three sepals below the flower, which helps identify this versus other buttercup species. Fruits are small and innocuous. Bulbils can be seen on the ground after the plants senesce.

Lesser celandine plant. Photo by Caroline Marschner of Cornell University.

Lesser celandine bulbils. Photo by Lelsie J Mehrhoff of the University of Connecticut, via Bugwood.org,

Lesser celandine root structures. Photo by Caroline Marschner of Cornell University.

Lesser celandine seeds. Photo by Leslie J Mehrhoff of the University of Connecticut, via Bugwood.org.

Management: very small infestations of a few plants can be removed by digging up the plants and carefully removing all plant material including bulbils and tubers. Larger infestations are much more difficult to remove. Most authorities recommend treatment with an herbicide after leaves mature but before flowering begins, in early spring. This method is complicated by the plant’s common location near water; make sure any herbicide used is safe for use near water and allowed in your state.

Similar Species: Marsh marigold (Caltha palustris)

The New York native plant marsh marigold (Caltha palustris) is another riparian plant with yellow flowers on the same flowering schedule, but it has larger leaves and flowers with five broad petals. Marsh marigold has fibrous roots with no storage structures, and no bulbils forming on the aboveground plant.

Marsh marigold (Caltha palustris). Photo by Caroline Marschner of Cornell University.

Marsh marigold (Caltha palustris). Photo by Caroline Marschner of Cornell University.

Further Reading

CCE Oneida county has a good description of the species and management suggestions: https://s3.amazonaws.com/assets.cce.cornell.edu/attachments/23004/Greater-and-Lesser-Celandine-2013.pdf .

Ohio State University resource for lesser celandine: https://bygl.osu.edu/node/1016

Lesser celandine management from the Little Falls Watershed Alliance outside of DC: https://www.lfwa.org/updates/tips-controlling-lesser-celandine


Distinguishing Mustard Varieties

Barnyardgrass seedling. Photo by Steve Dewey of Utah State University, via Bugwood.org

Early Plants

Early plants can be typically be identified according to their cotyledon, first true leaves, and/or the stem.

Mature Plants

Non-flowering/Basal rosette

Flowering plants


Uva R H, Neal J C, DiTomaso J M. 1997. Weeds of the Northeast. Book published by Cornell University, Ithaca NY. The go-to for weed ID in the Northeast; look for a new edition sometime in 2019.

Cornell University’s Turfgrass and Landscape Weed ID app. Identification and control options for weeds common to turf, agriculture, and gardens in New York; uses a very simple decision tree to identify your weed.

Spreading Dogbane

Spreading dogbane in hay field. Photo by Josh Putman of Cornell Cooperative Extension.

Spreading dogbane. Photo by Josh Putman of Cornell Cooperative Extension.

Early July, 2020

Josh Putman is Cornell Cooperative Extension’s SWNY Dairy, Livestock & Field Crops representative. He recently ran across this plant in a hay field that had not been worked for a few years. Spreading dogbane, Apocynum androsaemifolium, is in the same family as milkweeds and swallowworts, and the same genus as hemp dogbane. This perennial plant is found in open, dry areas and in disturbed habitats throughout New York and most of the US and Canada.

Leaves: Leaves are oval, 4-6cm (around two inches long), with smooth edges and pinnate veination. They are arranged opposite each other on the branch.

Mature Plant: 0.6m (2 feet) tall, although some sources say 2-5′, with branching reddish stems. Flowers are found at the ends of branches.

Flowers/Fruit: Flowers are bell-shaped with 5 petals that are fused to form the bell and then curl outwards. Flowers can be white as were seen in western NY, but can also be pink or white with pink striping. Fruit are a long, narrow pod up to 11cm (over 4 inches) long; each flower produces two seed pods. Inside the pods are many small seeds with fluffy tufts, much like milkweed or swallowwort seeds.

Toxicity: Dogbanes are reported to be toxic to livestock, containing a compound that interferes with heart function. This toxicity persists when the plant is dried as well as when fresh. There is no specific information on the toxicity of this species to livestock.

Management: Management information for this species in agricultural settings is sparse; most resources discussed it in the context of a native wildflower/shrub. In blueberry fields, nicosulfuron mixed with surfactant suppressed spreading dogbane (>60%), and dicamba spot sprays were over 80% effective. Glyphosate spot sprays worked better than hand pulling, and wiping with glyphosate was also effective (Wu and Boyd, 2012). In an early experiment from the 1940s, dogbane was partially susceptible to 2,4 D (Egler 1947). In a forest setting, aerial application of glyphosate did not control spreading dogbane (Pitt et al 2000).


University of Maryland Extension Toxic Plant Profile: Milkweed and Dogbane: https://extension.umd.edu/learn/toxic-plant-profile-milkweed-and-dogbane

Ohio State University Perennial and Biennial Weed Guide: Hemp Dogbane. https://www.oardc.ohio-state.edu/weedguide/single_weed.php?id=40

Lin Wu and Nathan S. Boyd. 2012. Management of Spreading Dogbane (Apocynum androsaemifolium) in Wild Blueberry Fields. Weed Technology 26(4)777-782.

Frank E. Egler. 1947. 2,4-D Effects in Connecticut Vegetation, Ecology 29(3)382-386.

Frank E. Egler. 1949. Herbicide Effects in Connecticut Vegetation, Ecology 30( 2) 113-270.