YELLOW RATTLE SPRINGWATCH 2015
Spring made its first appearance in our meadows at the beginning of March with the emergence of yellow rattle seedlings.
Seeds that were either sown last autumn, or shaken from hay in summer, have spent the winter lying on the wet soil surface exposed to winter weather. Rather than being an endurance test, as one might imagine, this is just the stimulus yellow rattle seeds require: 3 or 4 months of prolonged chilling release yellow rattle seeds from their enforced dormancy. In this primed condition the seeds are set to germinate at the first sign of spring.
As with bumblebee queens, frog-spawn and other indicators of spring the first appearance of yellow rattle varies from year to year: the first week of March is in our experience typical for eastern England.
Germination of yellow rattle in our open meadows was first observed on March 9th; right on cue in spite of the fact that we have not much in the way of frost this winter and no snow. This demonstrates that yellow rattle seed just need chilling rather than freezing to trigger germination. A cool or mild winter is still sufficient to synchronise yellow rattle germination in spring.
This synchronised early emergence of yellow rattle is critical: the seedlings must grow quickly to grab space before the surrounding spring flush of grass closes in and denies them light. If successful, the young plants will soon attach themselves, via their roots, to nearby grasses and other plants to extract nutrients from them. Yellow rattle will flower in early summer and complete its life cycle when its seeds ‘rattle' out to fall back to the ground in July.
Posted on 09 March 2015,