Many new gardeners recognize a nettle, buttercup or dandelion but so often I hear someone say "I wouldn't know if it was a plant or a weed". Many weeds are simply plants that grow invasive and usually where they are unwanted. I have put together a few of the ones that can often crop up in allotments and tried to simplify the facts as to how it will effect your plots, PLEASE add any others that you know off.
CREEPING BUTTERCUP: This is a troublesome weed that withstands some trampling, whilst it looks pretty in flower it slowly depletes the land of potassium. The seeds that disperse from the plant can stay in the soil for five to seven years. Chickens and geese love to eat the leaves.
SHEPHERDS PURSE: ( A member of the mustard family) This plant produces hundreds of seeds, it can easily spread and needs to be removed before it flowers. This plant is edible and the leaves are rich in vitamin c and k and can be used in salads, the seeds and pods can be used as a seasoning in soups.
FAT-HEN (goosefoot lamb) this is another troublesome weed that is very efficient at extracting nutrients from the soil. It can contain potentially harmful levels of nitrate and enriching the soil increases its frequency. Rich in vitamin c it was used prior to the 16th century as a vegetable now replaced in the modern diet by spinach and cabbage.
HORSETAIL (mares tail) Found mostly near streams and damp soil conditions, this weed is so deep rooted it is hard to remove so becomes invasive quickly. The roots can go to a depth of 2m (7ft). this plant is VERY poisonous if consumed.
GROUNDSEL (chicken weed) Acting as a host for leaf rust and fungus this weed can cause black root rot in peas, it can also carry seed transmitted virus diseases that attack crops. Large quantities eaten by animals can cause liver damage. Make sure it is clear of the manure heap, it can contaminate that too.
GROUND ELDER: Vigorous and spreading and often growing over cultivated plants, depriving them of light, water and nutrients. try to remove the whole plant before it flowers and sets the seed.
OXALIS (common wood sorrel, lemon clover) I find this weed a nightmare in my plot. It always appears simple to remove but the little bulbs can camouflage the area and then it just keeps on coming back. This plant is definitely no herb and the only medicinal effects it has in my personal opinion is the headaches and high blood pressure I get with it, even your slugs cannot eradicate this one.
COMMON CHICKWEED One of the most commonest weeds in the UK and one to watch near over wintered vegetable crops. This plant carries viruses in the seeds that can pass on to infect neighbouring plants, The virus stays in the seed, buried in the soil for up to five months. Ants can transport the seeds and they have also been known to be present in manure. This is rich in vitamin c and the leaves are sometimes used as a salad vegetable.
CLEAVERS (goose grass stickywilly) HERBAl This troublesome plant is the invading sticky weed, it climbs and clings to crops and hedgerows restricting growth and water supply. Cleavers has been used as a vegetable but before the pods appear the plant was once used for problems with the lymph system i.e. Tonsillitis The fruit from this plant has been used as a coffee substitute because it has less caffeine.
HAIRY BITTERCRESS (mustard family) HERBAL. This annual which can spread rapidly by seed can quickly spread to infest the whole allotment, during its lifecycle of three to four weeks it disperses thousands of seeds. The seed spreading plant needs to be removed before it spreads quickly around crops, It can survive through winter and likes areas where moisture is present. The herbal weed can be consumed and has a peppery rocket type flavour its used as a salad leaf or can make a good pesto sauce.
GIANT HOGWEED (DANGER) this can grow up to 20ft tall and is highly invasive, this turns up around the UK in hedgerows around the countryside, keep check of unused neighbouring allotments. This plant is considered dangerous it can cause severe burns to the skin and cause a condition called Phyto-photodermatitis. the skin will redden followed by burning and blistering, after several months the skin can remain sensitive to light and can last for a number of years *USE GLOVES and COVER LEGS and ARMS.* Remember clothes and tools can be contaminated and be also potentially hazardous.
FIELD BINDWEED (bearbine) This is one of the most problem weeds I personally come across every year, and the reason is it is awkward to eradicate because the depth of the root system which can go as deep as 5m's. This plant trails over the ground and climbs through all the plants in its vicinity pulling them down and hindering the growth. The seeds can lay dormant in the soil for over twenty eight years. One nice good point about the bindweed is it is very much loved by butterflies.
Remember is you are adjacent to an empty plot that has been left unattended, the weeds growing if left to seed will quickly crop up in your plot. It is always a good idea to round up a few other allotment holders for a few hours and clear the land when weeds are in abundance. I am sure they will help for an allotment BBQ when its finished.