Tag Archives: blue

Where Blue is a Rare Colour in Nature. Roella recurvata and its Blue Pollen.

By Karin Sternberg

Stepping into the fynbos brings untold surprises and beauty with it. Writing this now in mid-February, a difficult time for this floral kingdom in the face of mid-summer heat, extreme winds and very little to no rain, we are once again marvelling at nature’s intelligence and the interaction between plants and pollinators.

The Roella recurvata flowers are a South Peninsula endemic known from fewer than 5 sub-populations. They are a source of abundant pollen for bees. The pollen is mostly blue! Yet blue is a rare colour in nature, so what is the significance of this colour for pollen? Why of all the colours is it blue? Perhaps it has some ultra-violet colouration that we cannot see, but that might be a brilliant colour for the bees with their ultra-violet vision?

Presently there is very little forage for bees. January/February is always the most challenging time for bees to find forage in the winter rainfall regions and the colonies dwindle to a minimum. But the wild nest we are monitoring close to this sub-population of flowers is doing very well and they are busy, carrying in their heavy loads of pollen packed tightly into their pollen baskets. This means that they are able to stock up on their pollen stores, but also that they have brood (babies) to feed! Drones are also present, where they are absent at all the other nests being monitored. In fact, at most other nests there is very little activity and very little pollen going in. Most of the wild honeybee nests are literally just ticking over, trying desperately to survive this period of dearth.

One possible reason for this flower bearing blue pollen may lie in careful observation of the photo with the pollen-foraging bees entering the depths of the nest. The blue pollen almost has a fluorescence or luminescence like quality to it. We found the following paragraph in Science Magazine (08 Aug 1975: Vol. 189, Issue 4201, pp. 476-478):

‘Nectar, which fluoresces in the visible and absorbs in the ultraviolet spectrum when irradiated by ultraviolet light, occurs in many bee-pollinated plants. It is suggested that these characteristics function as direct visual cues by which bees can evaluate the quantities of nectar available. Thus, they assume an important role in pollination of the flowers and foraging efficiency of bees.’

These flowers with blue pollen, extraordinary as they are, possibly also have the capability to attract bees to it through a fluorescence, indicating their abundance of pollen, which possibly also has a high nutrient/protein content which is invaluable to the bees especially at this time of year.

So many questions arise when looking at nature and when trying to understand nature’s intelligence. One realises just how important the ecology and biodiversity is for the survival of both plant and pollinator. In this example, one cannot separate the flower from the bee. It has possibly evolved over time to develop this extraordinary visual cue not to be missed when pollinators are least expecting it.

A solitary bee on Roella recurvata

(All photos are copyrighted and are thus the property of the authors. If you wish to use any, please contact us at ujubeeconservation@gmail.com)

The author at work amongst the Roella flowers:

Karin Sternberg