Biennial weeds

Biennials normally reproduce by means of seed but, unlike annuals, they rarely flower and set seed in their first year. The first years growth represents a vegetative phase during which the plant grows and accumulates food reserves followed by flowering and seed production in the second year. After the plant flowers and sets seed it normally dies. The vegetative phase might last more than one year in unfavourable conditions or, conversely, flowering may occur in the first season under favourable conditons. Management methods will be similar to those employed against annual broadleaved weeds.

List of Biennial weeds

Caper spurge    
Evening-primrose    
Giant hogweed    
    Goat's-beard    
Hemlock    
Hogweed    
    Spear thistle    

Comments

  1. composite weed with small yellow flower heads
    - Anon. 2---1-2005

  2. We have a large persistent weed with rhubarb like leaves, what could this be and how do we erradicate it?
    - Elizabeth 8---0-2006

  3. There are 3 especially difficult weeds I would like to know the name of and how to deal with that persistently show up all over. I live in Denver, CO
    1. One is spreading along the ground with lots of stems and smallish rounded leaves, coming off one gigantic root in the center, that always turns 90 degrees underground so it's impossible to pull out. It will start producing small pinkish flowers if left alone. 2. The next two are tree-like and cause a lot of problems if they grow too big. One has spindly, almost hollow but robust stems and has large arrow-head shaped leaves. We have them all over the property. The other one;
    3. gets very thick stems and has a leaf with pointy compound leaves. These produce thick woody stems that will grow into humongous trees and are impossible to kill if they get to that point, because they just keep sprouting new growths, even if you chop them down. Help!
    - weedhater 5---0-2008

  4. aren't there any more?
    - courtney 9---0-2008

  5. does it affect annual crops
    - Dharmraj nayan 1---1-2008

  6. does it affect perennial crops
    - nevena kristelle 3---0-2009

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