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
- 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
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 until it begins flowering. It is perennial, with their spiny leaves forming a flat bed. The flowers are deep pink in color and grow in the center of the cluster of leaves growing in a circular pattern.
Giant Foxtail (Setaria Faberi): This is a type of grass that grows erect. Its hairy ligule and the dense hair that grows 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 stems that are thin and wiry that twine around anything close by. The flower is shaped like a trumpet, and can be white or a light pink in color. Its rootstock is woody, and it is very hard to get rid of. It has a perennial life cycle.
Stinging Nettle (Urtica dioica): This is of course 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 weed is a problem in tilled and alfalfa fields, and in pastures. Once the seedlings and plants get established they can interfere with the establishment of cultivated species like legumes. Dandelion reproduces via seeds, and is a perennial plant. It is practically stemless and the leaves grow in a rosette, which are lobed and long, and have variable shapes. The flower is bright yellow in color, which grow 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 are one of the distinctive features, usually purplish, with large sized seeds that look like millets which grow concentrated on spikelets. These are regarded as one of the worst weeds, which cause crop yield reduction and the failure of forage crops due to 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.