Horseweed is a North American herbaceous annual plant with a hairy stem, numerous pointed leaves, and waxy inflorescence. It has been naturalized in Eurasia and Australia, where it is a common weed in urban and agricultural regions. Horseweed can be used in a survival situation to start a friction fire.

While native to North America, the annual fleabane has been introduced to other places around the world, as well as in 43 states of the United States. It is a popular choice for bees, flies, wasps, and butterflies as a source of nectar, but is invasive and is threatening the native ecosystem where they grow.

While the redroot amaranth is considered a weed in most areas, some parts are edible. Fresh leaves may be included in soups and stews, while the dried leaves can be utilized in tea or ground into flour for bread or used as a thickening agent. Seeds can also be eaten, but the stalks, roots, and older leaves contain toxic substances. Redroot amaranth is sometimes used as fodder for livestock - it is nutritious in small amounts but toxic if too much is fed over a span of several days.

The common cocklebur (Xanthium orientale) is a variant of Cocklebur from the regions neighboring the Mediterranean. It is considered to be a weed as it invades cultivated land, outcompetes growing crops, and is toxic to livestock.

Annual ragweed (Ambrosia artemisiifolia) is one of the most notorious weeds in the world. It is an annual herbaceous plant with highly allergenic pollen and a very vigorous spread. Annual ragweed is a very competitive species, which is why its presence in cultivated plants is highly undesirable.

Gallant soldier (Galinsoga parviflora) is named after the Spanish botanist Galinsoga for the genus, and parviflora means it has many small flowers. It is a plant species related to the sunflower, though its flowers are tiny. Nevertheless, each plant generates thousands of seeds. This species is poisonous to goats so ranchers need to avoid this weed as much as possible.

Experts consider johnson grass (Sorghum halepense) to be one of the ten worst weeds in the world. If frost or heat causes the plant to wilt, it can produce enough hydrogen cyanide to kill livestock. It grows at such a prodigious rate, it can choke out other crops. It’s named after Colonel William Johnson, an Alabama plantation owner who sowed lots of its seed around 1840.

Lambsquarters has many other names, including pigweed, goosefoot, and bacon weed. This plant seems to appear out of nowhere and is considered by many to be a pesky weed. However, the greens of this plant are edible, can be prepared similar to spinach, and are packed with nutrients.

Portulaca oleracea, colloquially known as common purslane, is an annual succulent species with reddish stems and tiny yellow, five-petal flowers. It is used for culinary purposes in various parts of the world, most often raw, in salads. Common purslane is also a good companion plant for crops that thrive in moist soils.

Birdeye speedwell (Veronica persica) is a plant species native to Eurasia. It has been introduced all over the world, but is generally considered to be a weed because it can adversely affect soil health. The fruit of the birdeye speedwell is roughly heart-shaped, with two lobes that angle away from each other.

Ribwort plantain grows in a number of different habitats as long as it has enough sunlight. Its leaves have characteristic parallel veins that make it easy to identify. The heads of ribwort plantains get popped off in some common British children's games. Its seeds are critical food sources for songbirds, and its leaves are eaten by rabbits and deer.

Orchard grass (Dactylis glomerata) is native to Eurasia and was introduced to North America around the 18th century as a forage grass. Now it is widely naturalized in the U.S., Australia, and New Zealand. It is also called "cat grass" because our feline friends love to chew on it.

Common bird's-foot trefoil (Lotus corniculatus) is a common flowering perennial plant that grows widely throughout Europe and North America. Commercially, it is often added to livestock feed to prevent bloating. In Britain, common bird's-foot trefoil is often referred to as "butter and eggs" due to its flowering appearance and golden color. It attracts bumblebees and is considered an invasive species in North America and Australia.

Cynoglossum officinale, houndstongue, or Hound’s-Tongue is a member of the borage family with a distinctive odor, giving it another name, Rats and Mice. Its unpleasant fragrance is said to ward off rats. Classified as an invasive and noxious weed, this plant is toxic to livestock.

Meadow buttercup (Ranunculus acris) is a flowering plant native to Europe. It has gained many nicknames related to its yellow flowers and ubiquity in meadow-like environments. Meadow buttercup is moderately toxic to both humans and livestock.

Lacy phacelia flowers open in a sequence that allows for a long flowering time, which is why it attracts bumblebees, honeybees, and other pollinators. It is typically grown in vineyards and along agricultural fields. This plant is native to the southwestern United States and is grown as a cover crop, green manure, and decorative plant.

The black medick plant matures anywhere from 15 to 79 cm in height, with stems that lie flat at the beginning of growth and later stand up to be erect. The black medick is a plant known for making excellent honey. It is sometimes planted specifically for this purpose. It is also a good pasture plant for livestock feed; however, it is not overly palatable to cattle.

Golden crownbeard (Verbesina encelioides) is an annual flowering plant species related to the sunflower. Golden crownbeard is also commonly called a butter daisy. This plant produces a strong odor when crushed. Its flowers, nectar and seeds are eaten by insects, butterflies and birds.

Narrowleaf evening primrose (Oenothera fruticosa) is a flowering plant native to North America. The narrowleaf evening primrose grows in woodland areas and dry rocky soils and sometimes cultivated as ornamental plants. The taxonomy of this species is controversial in the scientific community, they can interbreed freely with many other evening primroses.

A member of the daisy family, Galinsoga quadriradiata can be an invasive weed that is especially harmful to organic crops. The sticky seeds can hang on to livestock and people, creating an additional nuisance. Each plant can produce over 7000 seeds, and it can reduce crop production by up to half.