A lot of times we as photographers would increase the contrast in a photo in post processing. Usually by adjusting the levels slider or by increasing the black levels in a photo. Another way to do it is click the photo with high contrast. You can use artificial light ranging from a hand held torch to strobes/flash light or even the sun. Usually our eyes prefer photographs with higher contrast. You can also do it with colour but lets save that for another time. Here is a photo I clicked with an off camera flash in manual mode.
Settings Shutter speed 1/60 f/22 Lens 35MM with a macro attachment.
There has been a minor levels adjustment to increase the blacks a bit. But for the most part this is straight out of the camera. Also the flash has fired from behind the leaf. This highlights the form of the leaf. If the light came from the front the image would have been flatter.
