Photos are great, but illustration can be better for specific purposes.
I love illustration of plants and vegetables, especially the old school botanical drawings and also this 70s inspired style of illustration. One of my most treasured books is a children's Gardening Book by John Seymour (1978) because of the beautiful illustrations. One of the real benefits of these illustrations is showing the different stages of plant development in one picture. Aspects can be emphasised, even if they are not a reality. For example, the pea pods are open here which doesn't happen, but it shows you where to find the peas.
One of my plans is to make some education plates for the plants in the community garden, along with illustrations of the plant in different stages of development so that people know what's what and how it grows. Often people aren't sure if the plant is a root vegetable, or if it will grow from a flower, or when it's ready to harvest. Illustration showing the different stages is perfect for this sort of situation!