Weeds are wild plants that have deleterious effects on cultivated land . Here are a few types of weeds that are commonly found.
Weeds are disliked by farmers and gardening enthusiasts. So much so, that they have been given various derogatory definitions, such as plants that are pernicious, persistent, competitive, and hamper human activity.
A plant that grows where it is not wanted; A plant that is not sown intentionally and is therefore out of place; Plants whose qualities have not been discovered yet.
Distinctive Features of Weeds
Irrespective of how they are defined, according to humans, the undesirable qualities of weeds far outweigh beneficial effects they may have.
Here are some of their main characteristics:
• They produce seeds abundantly • They establish themselves and spread rapidly • The seeds remain dormant for a long time • The buried seeds survive for a long time • They adapt to various conditions in order to spread wider
Weeds have various negative effects. Mainly, by competing for space, nutrients in the soil, light, and water, they impact crop yields negatively.
Some of the other negative effects on agriculture are:
• Insects use them as shelter for overwintering • They harbor crop diseases • They interfere with the harvest • They contaminate the produce, thus reducing their quality • They produce chemicals that are poisonous to humans, animals, and crop plants
Various Types of Weeds
There are about 250,000 plant species around the world, and about 8000 species, or 3 percent, of them are considered to be weeds. Here are some of the types of weeds that are commonly found in our gardens and fields
Ground Thistle (Cirsium acaulon)
This type grows hidden in grass and can remain undetected till it flowers. It is perennial, with spiny leaves forming a flat bed. The flowers are deep pink in color, grow in the center of the cluster of leaves in a circular pattern.
Giant Foxtail (Setaria Faberi)
This grass grows erect. Its hairy ligule and dense hair growing on the surface of the upper leaves are what differentiates it from other grasses. It usually is found amongst cultivated crops. It has an annual life cycle.
Field Bindweed (Convolvulus arvensis)
This weed has thin and wiry stems that twine around anything close by. This perennial trumpet like flower can be white or light pink in color. Its rootstock is woody and is hard to get rid of.
Stinging Nettle (Urtica dioica)
This is quite a familiar weed, and gardening enthusiasts are well aware how difficult it is to get rid of it. That is because it spreads via seed, roots, as well as stolons.
Its stem is woody and resists normal strimming. Its leaves are wrinkled and deep green in color, with strings of tiny flowers that are green in color. And of course it has nettles that sting, although it is supposed to have herbal uses.
Ivy (Hedera helix)
This is one of the most common creeper weeds that grows on walls as well as trees. When it grows in the tree canopy, it often covers the branches, gradually killing the trees.
When it grows on the ground it displaces native plant species the leaves are usually heart-shaped and have 3-5 lobes. The flowers are clustered and greenish-yellow in color. The young plants propagate rapidly, forming roots as they grow, and are harder to remove once they get established.
Dandelion (Taraxacum officinale)
This is a problem in tilled and alfalfa fields, and in pastures. Once the plants establish, they can interfere with establishment of cultivated species like legumes. It is a perennial plant, reproducing by seeds.
It is practically stemless and the leaves grow in a rosette, lobed and long, and have variable shapes. The bright yellow flower grows on a long stem, about 11-18 inches high. The seeds are attached to a hairy parachute, which are carried by the wind.
Barnyardgrass (Echinochloa crus-galli)
This is a type of annual grass that has flat, long leaves that are usually purplish color at the base. While generally they grow upright, however some of them can be spread out on the ground. The base of the stem is flattened.
The seed heads is one distinctive feature, usually purplish, with large sized seeds that look like millets which grow more on spikelets. These are regarded as one of the worst weeds, reducing crop yield and failure of forage crops by removing about 80 percent of the nitrogen in the soil.
It also accumulates high amounts of nitrates which can poison farm animals. It also harbors a number of viral diseases, and mechanical harvesting can be hampered when they grow heavily.