Leaves. Bark. Bone. Stone. Seeds. Nature's forms offer an extraordinary range of shapes, colours, tones and textures.
These images are a selection of entries from the Natural Forms category of our Photo Showcase. You can see more on Flickr. Entries to the showcase are now closed, but we hope you continue to enjoy those images that were submitted by photographers around the world.
What makes a strong photograph? Look for contrast, symmetry, pattern, and progression. Think about colour, shape and texture. And see how expert photographer Charlie Hopkinson approached his task when he photographed seeds for the Millennium Seed Bank at Wakehurst Place (more).
We asked Charlie for his tips:
Start by trying to isolate the subject from its surroundings, and concentrate on keeping it very simple. Watch out for what is in the background. Try different lighting conditions, and don't be shy about trying everything. A tripod is often very useful.