We are in the midst of 'buttercup month' at the moment.
On the drier grasslands (e.g Hutchison's meadow and many churchyards and road verges), bulbous buttercup - Ranunculus bulbosus has been in bloom for a week or two, adding some welcome yellow 'sunlight' to the rather rain swept days of April and early May. A frequent companion of one of the earliest flowering meadow grasses - sweet vernal grass - Anthoxanthum odoratum, bulbous buttercup is easily distinguished from other buttercups, by it softly lobed leaves and its down-turned or reflexed sepals.
Often at least a fortnight of so later, meadow buttercup - Ranunculus acris begins to flower - carrying its much taller flowering heads up into the hay. It also has a much more cut or dissected leaf.
Meadow buttercup is the buttercup that creates the beautiful haze of yellow seen in hay meadows - often flowering at the same time as common sorrel - Rumex acetosa - the yellow buttercup contrasting dramatically with the red sorrel.
For me, 'buttercup month' also means returning to the office after a meadow visit with my shoes or boots covered with yellow dust from the petals and pollen!