A good case of live and learn associated with this species. We’ve noticed the leaves on many of the Cleavers plants in the Garden ending up looking like those shown below. On the left we see a Cleavers in its typical state, with leaves arranged in outward pointing whirls. On the right we see the leaves distorted and rolled.
We had always considered this distortion to be natural, just the plant aging. However by accident we found something online about cleavers having galls that looked just like this. We quickly popped down to the bottom of the garden and were not surprised to find plenty of such galls on a good number of plants, including recently germinated ones such as the one below showing both healthy and parasitised leaves.
This distortion is the result of a tiny mite called Cecidophyes rouhollahi feeding on the sap of the leaves. It’s a tiny mite (0.3mm) and we may attempt to find one within a gall at some stage as they are odd looking creatures. Once it has finished with a leaf it is believed to walk its way to a new leaf on the same plant to start the process over again. However it is also suspected to use wind to travel to whole new plants when needed.