I guess one of the reasons they appeal is that those subjects have interesting colour and texture. Take a leaf, for example. So many species, so many colours. Some have darker veins, some lighter - lots of techniques can be used to depict them. There are also so many shades of green, with or without other colours. I often tell my students that if they were to just find and paint a new leaf every day they would learn so much about drawing, colour mixing and painting with watercolour.
|'Fallen Colour' watercolour. A3 Arches medium paper.|
|'Past Their Prime'. Ink and Watercolour, Arches medium 300gsm watercolour paper A2.|