Common whitlowgrass (Erophila verna) is not a grass at all, as you can see it is a flower.The four deeply lobed petals make this a member of the cruciferae (or cress) family. It is a tiny flower, less than three inches tall, but one that is worth a closer look under magnification.
The flower head of this plant is so small it is very easy to not see it in the first place! It grows where there is very little soil, often on concrete or tarmac in gutters of roads or car parks. Not only does it grow in harsh conditions it thrives in February and March, long before the majority of other flowers have even started to appear above ground. It can be pollenated by small insects but, flowering so early in the year, the species is basically self-pollentating.
Now someone out there will want to know why it is called whitlowgrass and I have no idea. My usual references source have not been of any use at all! The NHS website describes a whitlow as an herpetic abcess at the end of the finder caused by infection with the herpes simplex virus (the cold sore virus). One can only surmise that this plant was believed to be a cure for whitlows.