Plant Clones and Cuttings

Define natural cloning in plants.

• The production of genetically identical offspring from a single parent plant through asexual reproduction.

What is vegetative propagation?

• The process by which a plant grows a new, genetically identical shoot from a vegetative part (stem, root, or leaf) rather than from a seed.

What are bulbs?

• Swollen leaf bases storing food (e.g., onions, daffodils). Buds form internally and develop into new shoots.

What are runners?

• Horizontal stems growing above ground on the surface (e.g., strawberries). Roots develop where they touch the soil.

What are rhizomes?

• Horizontal stems growing underground, often swollen with stored food (e.g., ginger, marram grass). Buds develop into new vertical shoots.

What are stem tubers?

• Swollen underground stems (e.g., potatoes). The "eyes" are buds that sprout into new plants.

What are suckers?

• Shoots that grow from adventitious buds present on the shallow roots of a parent plant (e.g., elm trees, blackberries).

Describe the step-by-step method for taking a simple stem cutting. (6)

• Use a sharp, sterile scalpel to cut a healthy, non-flowering stem.

• Make the cut at a slanted angle just below a node (the joint where leaves attach).

• Remove the lower leaves from the cutting.

• Dip the cut end into rooting powder.

• Plant the cutting into a pot with well-aerated, moist compost.

• Cover the pot with a clear plastic bag and place it in a warm, well-lit environment (but out of direct, scorching sunlight).

Why must you remove the lower leaves from a stem cutting?

• To drastically reduce the surface area available for transpiration (water loss). Because the cutting has no roots yet, it cannot replace lost water easily and would wilt and die.

Why is the cutting covered with a clear plastic bag?

• To trap water vapour around the leaves, creating a microclimate with high humidity. This reduces the water vapour potential gradient between the leaf and the air, further minimizing transpiration while roots grow.

What is the active ingredient in rooting powder and what does it do?

• Auxins (plant growth hormones). They stimulate cell division and the differentiation of stem cells into new root tissue.

Describe the difference in structure and location between a runner and a rhizome. (2 marks)

1. A runner (stolon) is a horizontal stem that grows above the ground on the surface.

2. A rhizome is a horizontal stem that grows underground and is usually swollen with stored food.