Pollen plants explained

Nectar is fuel, pollen is bodies

Adult bees run on nectar. Larvae are built from pollen, which supplies protein, fats, vitamins and sterols. A colony can survive a short nectar dearth on stores; a pollen dearth stops brood rearing within days.

This is why spring pollen matters disproportionately. A bumblebee queen emerging in February needs pollen to provision her first cells within days of finding a nest. Without it there is no colony, however much nectar is available.

The pollen-only plants

Several plants offer abundant pollen and no nectar at all. Poppies, dog rose, St John's wort, California poppy, anemone and most of the Ranunculaceae are in this group. Bees visit them purely for pollen, frequently buzzing the anthers to release it.

Pollen quality differs

Not all pollen is equally nutritious. Protein content varies from under 10 per cent to over 40 per cent by species, and amino acid profiles differ. Willow, clover, gorse and phacelia pollen are high quality; some wind-pollinated tree pollens are low.

This is why pollen diversity matters and not merely quantity. Colonies with access to several pollen sources show better immune function and survival than those on a single source, which is one of the more direct arguments against monoculture landscapes.

How bees carry it

The middle row is the important one. Because mason and leafcutter bees carry pollen dry and lose a great deal of it, they deposit more on each flower they visit than a honey bee does. Per individual, a mason bee is several times the orchard pollinator a honey bee is — a case where being untidy is the advantage.

The best pollen plants

• Willow — the critical early source, and only male plants produce it.
• Dandelion — abundant, early and free.
• Poppies and California poppy — pollen only, in quantity.
• Hollyhock and tree mallow — among the largest pollen grains of any plant.
• Dog rose and single roses — abundant pollen, no nectar.
• Crocus, scilla and anemone — early spring pollen when it matters most.
• Phacelia, borage and clover — good quality and abundant.