Lighting

The first photo is shot from an angle so the light basically only hits the highest section of the cactus, that section is shaped like a heart.  The rest of the photo below the heart is dark with the heart lit up and emphasized.  Above it is light and the heart connects and transitions between the two.  The second picture is from below the cactus up and out so the suns lighting's turns the cactus black and takes away the texture and color.  This helps to take the emphasis away from the cactus and put it on the bird that is caught flying through the frame.  The third photograph is peaking through the shaded cactus and into a lit up a whole.  The whole stands out due to the lighting.  Inside of the whole we are peaking through there is a window but you cannot make out the image which adds wonder some question to the photo.  The lighting allows you to chose where the audiences attention is drawn quickly.