In shady places there are a few native primroses (Primula vulgaris)
and in some years I planted a few specimens of ornamental varieties of polyanthus (Primula x polyantha) in the flower beds. Neighbouring gardens have polyanthus too and there are purple primroses – possibly the variety ‘Wanda’. Some differences between true cowslips and primroses are that the former have smaller flowers clustered to one side at the top of tall main stems with short hairs. Primroses have larger flowers on individual short stems with longer hairs. Every year I allow my wildflower and lawn plants to set seed, cutting the small meadow in patches from July to September. Then the entire area is cut and finally mowed with the lawnmower. This regime means that there is natural cross-pollination of the Primula mainly by bees, followed by seeding and germination of new plants. Over the years I have noticed increasing numbers of Primula hybrids in my garden. Some hybrids seem closer to cowslip/primrose crosses with pale yellow primrose type larger flowers born on all sides of longer or shorter stems
Those with the shorter stems tend to be more hairy than those with long stems. Some other plants seem to be primrose/cultivated polyanthus crosses of various shades of yellow and pink to mauve and some have multiple flowers on the stems
Primroses tend to flower slightly earlier than cowslips so providing some genetic segregation in the garden. In natural communities primroses are more frequent in shadier areas and woodland, while cowslips tend to be in grassy meadows on calcareous soils. Botanically hybrids between our native primrose and cowslip are known as false oxlips (Primula vulgaris x veris). The true oxlip (Primula elatior) is a woodland species which is only abundant in woodlands on clay soils in some counties in eastern England – it does not occur in Dorset. The cowslips in my garden seem to be changing more than the primroses, especially in one small area which was planted about 17 years ago. Possibly over the longer term the cowslips will be swamped by the more successful primroses. A gardening friend is so concerned about the dilution of the native stock by hybrids between Primula species that she removes the flowers off any that do appear and if time even digs out the offending plants in her garden. However in the wider countryside there are many records of these hybrids and some genetic types may adapt well to urban areas and a changing climate.