1. 2.5 Asexual reproduction in plants

2. Propagation  Asexual reproduction: Asexual reproduction is a mode of reproduction by which offspring arise from a single parent, and inherit the genes of that parent only, it is reproduction which does not involve meiosis  It is used to increase the supply of rare plants

3. Advantages  Only one parent is required and the offspring is/are a genetic identical to the parent  Another name is – vegetative propagation  Forms of this include:  Runners  Grafts  Corms  Bulbs  Cuttings etc 

4. Lignotubers  Is a swelling at the base of a stem that is a source of dormant buds. Buds are growing points of plants. Underground lignotubers

5. Lignotubers

6. Epicormic buds  These are buds found under the bark, which need a form of stimulation in order to grow.  A trigger for growth is usually fire  it destroys a chemical that inhibits growth

7. Epicormic buds

9. Runners  Runners are long stems that grow from the crown of the plant.  They usually grow from a bud near the soil surface  Grasses and strawberries are grown from runners

10. Runner pictures and diagrams

13. Propagation issues (p.105)  Commerical propagation of plants need to overcome the following issues:  LENGTH OF TIME: it takes time to grow a plant that is viable and not susceptible to disease  CARE FOR TRANSPLANTING: horticulturalist’s need to ensure that plants are fully established as transplantation can hinder growth

14.  BALANCE B/W LIGHT AND HEAT: providing light cont. will increase photosynthesis rates which increase growth rates. Yet, too much light can overheat the plants  AVAILABILITY OF PLANT STOCKS: rare plants may cause issues with propagation. If there is a limited stock of parent plants, continuous pruning and tissue removal can cause damage to the parent plant stocks

16. Benefits of Cloning (p.105)  Cloning allows the commercial propagation of plants that have desirable characteristics. It is also a valuable method of propagation of plants that are difficult to grow from seed  Clones of a plant are very similar in appearance to each other as they are grown from the same organism  Whether they are cloned from the root, stem or leaf they will grow to form an entire new plant

17. Cont.  It is currently a controversial issue due to the ethical implications of cloning animals and humans  Disadvantages: there are high costs associated with tissue cloning due to the cost, time and labour involved.  It also reduces the genetic variation in a species which may result in survival issues if the environmental conditions change

18. Tissue culture  This only needs only one or a few cells which give rise to a new plant  It is used for plants which are hard to grow from seeds or seed which are hard to store  Part of the meristematic tissue is taken from the bud of the parent.  Meristematic tissue is from the shoot

19. Tissue culture – THE STEPS  The tissue sample is as small as 1-2mm 2  It is soaked in a solution of sodium or calcium hypochlorite for 10 minutes and then washed in distilled water  The tissue is then grown in a nutrient solution until it forms a clump of cells  The clump of cells is cut into smaller pieces and the procedure is repeated several times

20.  The small clumps of unspecialised cells are stimulated to grow into tiny plantlets by the addition of plant hormones.  The plants are removed from the tissue culture flasks and grown the normal way  COPY FIGURE 2.62 from pp. 106