Study the weed plants illustrated by the diagrams below and use them to answer the following questions;
(a) ldentify the weeds, illustrated as I, Il, Ill, and IV by their common and botanical names.
(b)(i) State the agents of dispersal of the seeds / fruits of weeds represented by diagrams l and III.
(ii) Describe one characteristic of the seeds which aid the dispersal of the weeds illustrated by diagram I and llI
(c) Name the parts labelled A to H.
(d) Give three reasons why the weed represented by diagram IV is Difficult to Control.
Explanation
(a)
- I = Common name = Tridax, Botanical name= Tridax Procumbens,
- Il = Common name = Commelina, Botanical name = Commelina Spp
- lII = Common name = Pig weed, Botanical name = Boelaria diffusa
(b)(i) Agent of dispersal of fruit of I is wind while that of III is animal or man
(ii) The characteristic that aids the dispersal of l is that the seeds are numerous, powdery, and can easily be blown by wind because they are light while III, the fruits are sticky on an external surface that adheres to the body of animal/ skin or cloth of man and it is easily detachable from the plant.
(c) A= flower, B= spathe, C= fruit, D = leaf E = leaf, F = young shoot, G= rhizome / stolon, H= root
(d) The weed represented by diagram IV is difficult to control because;
- It has an underground stem (rhizome) that produces new shoots from its auxiliary buds even after cutting or burning.
- It has the ability to produce both roots and new Shoot from each node
- It is buried underground and difficult to uproot.
- It is resistant to burning because of its watery rhizome
- It is resistant to drought