MAVO Year 4 · Plants · Section 9.4
Reproduction in plants
Asexual reproduction
During asexual reproduction, new plants develop without fusion of sex-cell nuclei. Ordinary cell division involving mitosis produces cells with the same genetic information, apart from possible mutations. New plants produced vegetatively are therefore generally clones of the original plant.
- Cuttings: a piece of stem, leaf or other suitable tissue develops into a new plant.
- Tubers and storage roots: swollen organs store food; new shoots develop where suitable buds or tissues are present.
- Bulbs: short stems surrounded by fleshy storage leaves can form new bulbs and shoots.
- Grafting: a shoot or bud is joined to another plant's root system. The joined parts retain their own genetic information.
- Runners: horizontal above-ground stems produce young plants at nodes.
- Rhizomes: horizontal underground stems produce shoots and roots at several points.
Sexual reproduction
In sexual reproduction, genetic material from male and female sex cells combines, usually producing a new genotype. In flowering plants, reproductive structures occur in flowers. Meiosis produces spores which develop into pollen and embryo sacs; the sex cells form within these structures. Thus pollen grains are not themselves single sperm cells.
Calyx and corolla
The calyx consists of sepals, often green, protecting the flower bud. The corolla consists of petals, often conspicuous and attractive to pollinators. In wind-pollinated plants such as grasses, petals may be small or absent.
Stamens
A stamen is a male flower organ consisting of a filament supporting an anther. Pollen grains develop in the anther and are released when it opens. They contain cells that produce or carry the male gametes.
Pistils
A pistil includes a stigma, style and ovary. The ovary contains ovules, each containing an embryo sac with an egg cell. After compatible pollen lands on the stigma, a pollen tube can grow through the style towards an ovule. Following fertilisation, an ovule develops into a seed and the ovary usually develops into a fruit.
Glossary
- Calyx
- The sepals collectively, protecting the flower in the bud.
- Corolla
- The petals collectively, often helping attract pollinators.
- Bulb
- A short stem surrounded by fleshy leaves storing food, with buds capable of further growth.
- Grafting
- Joining plant tissues so a shoot or bud grows on another plant's root system.
- Filament
- The stalk supporting a stamen's anther.
- Anther
- The part of a stamen in which pollen develops.
- Sepals
- Flower structures, often green, protecting the bud.
- Tuber
- A swollen storage organ, such as a stem tuber, containing food reserves.
- Petals
- Flower structures often coloured or scented and involved in attracting pollinators.
- Stamen
- A male flower organ consisting of filament and anther.
- Pistil
- A female flower structure including stigma, style and ovary.
- Taking cuttings
- Growing a new plant from a detached part of another plant.
- Stigma
- The pollen-receiving surface of a pistil.
- Style
- The region connecting stigma and ovary, through which a pollen tube may grow.
- Pollen
- The collective term for pollen grains, which carry the male reproductive stage of seed plants.
- Pollen grain
- A small structure developing the male gametophyte and delivering male gametes through a pollen tube.
- Runner
- A horizontal above-ground stem that can produce young plants.
- Ovary
- The lower part of a pistil containing ovules and usually developing into a fruit.
- Rhizome
- A horizontal underground stem producing roots and shoots.
- Ovule
- A structure containing an egg cell within an embryo sac and developing into a seed after fertilisation.