LO 2.1 - Definition and classification of weeds

Question 1

How are weeds defined and classified?

Name the four ways.

Answer 1

• Annual
• Biennial
• Perennial
• Ephemeral

Answer 2

A weed is a plant considered undesirable in a particular situation:

• “a plant in the wrong place“

The term “weed” has no botanical significance

• A “weed” in one place might be a crop somewhere else

Question 3

What are some characteristics of Annual Weeds?

Annual weeds

Answer 3

Annual weeds

• Complete their life cycle in less than one year.
• They produce an abundance of seed.
• Most annual weed-seeds will remain in the seed bed for up to 7 years.
• Summer annuals germinate in spring
• Winter annuals germinate in autum

Question 4

What are Biennial weeds?

Biennial weeds

Answer 4

Biennials weeds

• Plants which live for two years.
• Usually, seed germinates in season one, in which the plant produces a rosette with a fleshy taproot.
• The plant elongates and produces flowers and seeds during the second growing season and then dies.

Question 5

Perennial Weeds, what are they?

Perennial weeds

Answer 5

Perennials are plants which live for more than two years.

• Usually perennials do not produce seed the year of establishment.
• Most perennials reproduce by seed AND by vegetative means.
• Simple perennials reproduce almost solely by seed.
• Bulbous perennials reproduce by bulbs and seed (e.g. wild garlic).
• Creeping perennials spread by means of specialized modified above-ground stems (stolons) or below-ground stems (rhizomes), as well as seed.

Question 6

Ephemeral Weeds, what are they?

Ephemeral weeds

Answer 6

Ephemeral weeds

Ephemeral weeds can go through several lifecycles in one growing season.

Examples:

» Chickweed

» Hairy bitter cress

» Groundsel

Effectively super-annuals