Flowers are the reproduction organs of plants and pollination can be referred to as the mating process of plants. To make sure pollination is taking place, plants have evolved brightly coloured flowers and scent to draw the attention of bees and other pollinators; this also explains why so few plants have green flowers. If we look at bees, we see that most of them are covered in dense hairs. When a bee visits a flower to collect either pollen or nectar, she will become covered with pollen grains and when she visits another flower, there is no doubt that some pollen grains of the first flower will fall on the stigma of the second flower. Flowers have developed so called sticky stigmas so that pollen grains will adhere to the stigma. Some plants such as poppies only offer bees pollen as a reward to say thank you for taking care of the pollination. Most plants however produce nectar to attract bees.
Above: Anthophora furcata, a solitary bee with a long tongue feeding on wood sage.
Nectar is basically a kind of sugar-water. The sugar content varies, depending on the species of plant, soil conditions etc. It is said that wild marjoram Origanum vulgare and Wall germander or Teucrium chamaedrys both have a very high concentration of sugar, above 52% in the case of germander and in marjoram the sugar content reaches 76%. Apart from sugars, nectar contains amino acids, proteins, organic acids, vitamins.
Andrena synadelpha, a solitary bee feeding on wild marjoram.
Nectar is the fuel for our pollinators such as solitary bees, bumblebees, honeybees, butterflies, moths and bats. It is the only source of energy and without it, the pollinators cannot fly. Nectar is secreted by nectaries within the flower.
As flowers come in all shapes and sizes, it will not come as a surprise to learn that certain flowers will attract certain pollinators. Often, the so called “open access” flowers such as daisies offer not much nectar. Other examples are hawthorns, blackthorns, daisies, apples and corn marigold. Below a female Hylaeus bee species feeding on reseda (her white markings are small compared to the male below this photo)
And a male Hylaeus bee:
Many flowers are however designed to attract bees with a longer tongue.Such flowers offer more nectar compared to open-access flowers. This makes sense as long-tongued bees are larger and fly much faster so they need more fuel. Only a certain group of bees can access these flowers and that is good news for the plants as it means that they are certain to attract these specialists and pollination will be successful. We can say that long-tubed flowers and long-tubed bees evolved together.
Below a common carder bee, a bumblebee species with a long tongue
The tongues of short-tongued bees are only 0.5-3 mm in length; species like Hylaeus, Colletes and Andrena are bee species that fall within this category. Honeybees have a proboscis of about 6.5mm and the Bombus hortorum an impressive 14-16mm. The Hairy-Footed Flower Bee, the tongue length is even 19-21mm. This means that this bee can access nectar in flowers which is hidden deep within flowers such as Primulaceae species, lungwort and Lamiaceae species. The champion when it comes to tongue length is a moth called Cocytius cluentis from South America which has a tongue of 250mm.
Above: Heriades truncorum, a small solitary bee species with a short tongue feeding on corn marigold.
In your own garden, you can help bees and all other creatures such as this lovely beetle and female holly blue by providing lots of different plants and you will see that the corn marigold will attract different bees compared to dead nettles.
Picture yourself on a sunny day in May, perhaps with a nice cup of tea and watch the busy insects pollinating your flowers. A new, fascinating hobby will enter your life and this new hobby will reveal itself literally on your door step!