A few bees are out foraging for nectar and pollen. Hopefully, there will be more soon.
I have seen a couple of queen bumblebees attending their nests and the smaller native bees are probably doing the same. Be ready to watch their behaviour and what flowers they are going to. Note especially how much pollen they pick up on their bodies – lots and it is often from a variety of different plant species.
If a bee visits a lupin flower first and then goes to a daisy, like a sunflower, some of the pollen from the lupin can get deposited or left behind on the sunflower, but this does not mean that the sunflower will be pollinated. The lupin pollen must land on the female part of another lupin flower (i.e. the same species) for pollination to take place.
A flower’s female part that initially receives the pollen is called the stigma. It is often sticky, can be hairy, and may have microscopic grooves or indentations on it that are a perfect fit for the correct pollen (in this case lupin).
The pollen and the stigma recognize each other as being the correct ones by compatible fit and chemical compounds.
If they are a fit, the pollen grain will germinate, producing a pollen tube that grows down to the ovary via a stalk called the style. Carried inside the tube is the male nucleus (equivalent to the sperm nucleus).
The tube will keep growing until it reaches the ovary which contains one or more ovules. Each ovule contains an egg cell. The pollen tube fuses with an ovule allowing the male nucleus to enter and fuse with the female egg cell.
This process is pollination. To produce healthier, genetically stronger offspring (seeds) it is better if the pollen comes from a flower of the same species but located on a different plant to the flower containing the egg cell. This is called cross-pollination.
Self-pollination can occur in many plants, but if it does happen, it is often used as a last resort to produce seeds. However, seeds from self-pollination are not as genetically diverse and hardy as those derived from cross-pollination.
Plant flowers and their pollinators have evolved together over a very long time and have developed many features such as floral structure and colouration and attraction (e.g. perfume) floral rewards such as nectar and pollen, timing of flower openings and maturation of pollen or egg cells to ensure that cross-pollination takes place successfully.
Next time, I will give examples of interesting adaptations in both pollinators and flowers to encourage cross-pollination.
