Every spring the dog-violets appear and it is easy to dismiss them all as just 'dog-violets'. There are, however, four species that appear although the pale and heath violets are early summer rather than early spring. The most common and earliest flowering are the common dog-violet (Viola riviniana) and the early dog-violet and telling them apart can be a bit tricky.
The early dog-violet certainly comes out early in the year being in flower in March and is a few weeks ahead of its close cousin the common dog-violet which is more prevalent in April and May. The early dog-violet has a narrower flower than the common dog-violet but the colour of the spur on the back of the flower is usually the best way to tell them apart with the early having a spur the same colour as the flower whereas the common dog-violet has a pale, cream spur as you can see in my photograph.
Both species grow in open woodland, on hedge banks and verges; the early dog-violet perhaps preferring shade and so is also known as the wood dog-violet whereas the common dog-violet can be found in more open areas and can occur on pasture and grassland too.
Why 'dog' violets? Apparently they are scentless and are called dog-violets to differentiate between them and the scented violets, especially the sweet violet.