Iris flowers have a complex shape and curving petals, making them difficult to begin to draw. Build your sketch from simple shapes to detail. Here w learn to draw an iris from basic forms and place the petals using negative shapes.
Start with the central axis and proportions. Imagine a center line through the flower. This helps you see the symmetry and helps you draw a tilted flower. There are many ways you can draw your initial shape. I use simple shapes such as circles to rough out the form. Do not make this part of the drawing too complex. The goal of these first lines is to locate the major elements of the flower so that you can check the proportions. Double check your proportions before you continue. It is easy to change now. It will be difficult later.
Find the circles. Look carefully at the flower to find any circles in its structure that you can use as guides. Here I use three, the tips of the large (petal like) sepals at the bottom, the tips of the (petal like) pistil in the middle, and the tips of the erect petals. Note that from this view you are looking down on the first two circles and up at the last. The circles become more elliptical the closer they are to the level of your eyes.
Click on the first image to start a step-by-step slideshow.
With a non-photo blue pencil, block in the central axis, proportions and circles.
Draw in shape of the closest sepal. You do not have to capture all the angles yet, just their placement, length, and width.
Now place the other two sepals. Start by looking at the negative shapes between them to get the correct distance and spacing. You are not just drawing the sepals but the shape of the air between them.
Build up the pistil and petals on the top of the flower. I started by drawing the petal on the left, then the negative space on the left, then the middle petal, followed by the negative space on the right and finally the petal on the far right. The shapes of the negative spaces are as important as the petals themselves.
Start drawing the flower structures that are closer to you. Look for the angularity of the shapes. It is easy to over-round the petals so err on the side of overdoing the angles for a while to help you compensate.
Use the angles of the negative spaces to help you carve in the petals accurately. Consider the size of each petal and the size of the spaces between the petals. Clearly moving from front to back helps you keep your place as you draw a complex flower.
Add detail. The fine veins on iris petals reveal the curvature of the surface. Imagine that you can feel the undulations in the surface under your pencil as you draw. The gentle curves of these veins make an interesting contrast to the angularity of the petals.