Oilseed rape

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Oilseed rape : Brassica Napus

Plant : Oilseed rape has become a key feature of the beekeeping calendar and landscape in rural Northumberland.  It is mostly autumn sown in the region, which flowers in early spring.  Honey bees will travel 2 km or more for its nectar and pollen.  Although it is grown as a commercial crop it is common as a weed on roadsides and arable land.  The stems reach a height of 100 cm, with bright yellow flowers appearing on the top sections, which yield a dark 60 mm long seed pod.

Flower : Autumn sown Oilseed rape flowers between March and June.  The flower has four petals, which form the regular crucifix arrangement typical of the family.  There are four shorter sepals, 4 stamens and the ovary is superior..

Pollen : The pollen load of Oilseed rape is yellow.  The grain is round, although the pores can give it a triangular appearance.  It is approximately 27 um across and there are three furrow type apertures.  The surface is pitted and the exine is a medium thickness, with beading.

Rex Sawyer’s book, Pollen Identification for beekeepers is really helpful for understanding the features of pollen.  In Bob Maurer’s book, Practical Microscopy for Beekeepers, he shows some simple techniques for making up pollen slides.  Click here to return to plants for bees index.