This time of year because the trees are bare of leaves the exposed bark and branches are revealed showing some interesting forms. I have been stretching my knowledge and looking at this phenomena commonly known as lichens.
Lichens are composite organisms made up of a fungus and one or more algae living together. The algal partner produces essential nutrients for the lichen through photosynthesis, while the fungal partner provides the body in which they both live. The fungus produces spores in fruiting bodies (apothecia), which must germinate and find an algal partner before they can form a new lichen. In order to avoid this difficult stage many lichens produce minute fragments containing both partners, which can quickly colonise available habitats. These fragments can appear either as finger-like outgrowths (isidia) or sugar-like granules (soredia). (Ref NHM website)
These lichens take on different forms. The ones I have been noticing more recently are like the green ones in the photo particularly the one in the foreground. The other one in the picture has finer branching and has been less common. There were a number of the former at Winkworth Arboretum and around the woodland stream near Chiddingfold.
Lichens have often been used by model railway enthusiasts particularly one called Reindeer moss (Cladonia rangiferina), in the construction of scenery around the edges of a track in “00” Guage to represent bushes, tops of trees and shrubs.
Also in the photo are Cramp Balls (Daldinia concentrica) or as I know them most King Alfred’s Cakes so named because of the apocryphal story of King Alfred burning the cakes he baked. The scientific name may have something to do with the pattern of the rings that form inside the fungi. These cakes are useful when dried for tinder as they burn slowly with a bluey glow if I remember correctly.
If one puts this fungi into Wikipedia some more interesting facts can be discovered.