Primroses are named from the Latin prima rosa which means ‘first rose’ given their early flowering from December through May. They were traditionally given in bunches during Easter. Primrose Day has been celebrated on April 19th every year since 1881 in memory of Benjamin Disraeli, with bunches of primroses laid at his statute in Parliament Square. Primroses were his favourite flower and Queen Victoria would pick and send him bunches picked from Windsor Castle.
Wild primroses have great variation of colours from deep yellow to almost white or even pink, with horticultural societies some 200 years ago breeding new cultivars to grow in gardens and parks. They also noticed variations in the flower structure, a trait which helped develop our understanding of evolution and sexual reproduction in plants.
A pollination advantage
The primrose has two forms of flower, as seen below.
On the left, the female style and stigma (the pin like structure in the centre of the flower) are much taller than the male anthers and filaments (which provide pollen), which sit much lower down within the flower tube.
In the other flower form (right) this structure is reversed, with the anthers held high above the stigma and style.
Many naturalists had pondered the reasons for this variation, including the renowned botanist William Curtis (1746-1799), and Carl Linnaeus (the ‘Father of Modern Taxonomy, 1707–1778). Charles Darwin finally solved the riddle, identifying an evolutionary purpose to this ‘dimorphism’ (the existence of two different forms of a species, especially in the same population).
Although well known for his worldwide travels and discoveries, it was through observations and experiments from his home in Downe, Kent, that he refined his theories of evolution and natural selection.
In one experiment, he observed the effect of the different forms in seed creation. He transferred pollen between flowers of the same form, and also cross pollinated between different forms of the flower. Through this experiment he determined that cross pollination resulted in more seeds being produced.
Darwin also observed the pollinators of primroses, deducing that to be effective they must have long enough tongues to reach the nectar at the bottom of the flower tube. He concluded that having the two flower forms also maximised the potential for cross fertilisation to occur. In reaching the nectar in one form of flower, their tongues would pick up the pollen and transport it to just the right place if they then visited the other flower form.
Having the two flower forms therefore provided an evolutionary advantage for primroses – increasing pollination and the number of seeds produced.
A valuable source of nectar
Primroses provide a valuable nectar source early in the season. This is increasingly important as warmer winter temperatures due to climate change cause pollinators to emerge earlier when there are fewer flowers for them to feed on. Primroses provide nectar for a range of pollinators, including (as Darwin deduced) those with long mouth parts, such as the hairy-footed flower bee, bee-flies, moths and butterflies such as brimstone and small tortoiseshell (both of which overwinter as adults and therefore must quickly find nectar on awakening). Darwin also recorded how some bees with shorter mouth parts will ‘steal’ nectar without paying for the service by pollinating the flower, by chewing through to the nectar at the base of the flower.
Today the primrose is less common than it once was, largely a result of widespread habitat loss. However, this beautiful harbinger of spring can still be seen across the country in woodlands and hedgerows.
In the Royal Parks, primroses are found in the Woodland Gardens in Bushy Park and woodlands through Richmond Park, whilst we also plant primroses in ornamental beds, as a welcome addition for people and wildlife.