I just discovered that several of my rhododendrons have developed dark reddish brown bumps on their leaves. At first I thought they might be some sort of scale insect.

Inspection under a microscope showed that they were hemispherical and smooth on both sides. There was a protrusion on one end which appeared to have been broken or cut off when I removed them from the leaf. This seemed to have attached them to the leaf of even come out of the leaf. Cut in half, the masses had a dark brown outer skin and a uniform inside - a bit like a bean or a puffball fungus.

To me they look most like very tiny fungi. Does anyone have a guess what these might be?

a.m.