The mushroom is, according to Rudolf Steiner, ‘a flower without definition’. He says:
‘If you grasp what I have now said, my dear friends, you will grasp the idea of Spirit. I have said that the whole plant is really a leaf manifesting in different formations. This cannot be pictured in the physical sense; something must be grasped spiritually — something that transforms itself in every conceivable way. It is spirit that is living in the plant kingdom. Now we can go further. We can take a plant that is normal and healthy because its seed has been properly placed in the earth, it has absorbed the gentle sun of spring, then the full summer sun and has been able to develop its seeds under the weakening sun of autumn. But suppose a plant exists in such conditions of nature that it has no time to develop a root, an adequate stem, leaves or petals, but is obliged to unfold very rapidly — so rapidly indeed that everything about it lacks definition. Such a plant becomes a mushroom, a fungus.
‘There you have two extremes: a plant that has time to differentiate into all its detailed parts, to develop roots, stem, leaves, flowers, fruit; and a plant placed in such conditions of nature that it has no time to form a root, with the result that everything about it remains indication only; it cannot develop stem and leaves, and is obliged to unfold rapidly and without definition the principle underlying the formation of petals, fruit and seed. Such a plant only just manages to take its place in the earth and unfolds with amazing rapidity what other plants unfold slowly. Think, for example, of the corn poppy. After slowly putting out its green leaves it can proceed to unfold its petals, then the stamens, then the jaunty pistil in the centre. But a mushroom must do all this very rapidly; there is no time for differentiation, no time for exposure to the sun, which would bring the beautiful colours, because the sun is absent during its brief period of development. In the mushroom we have a flower without definition; development has taken place far too rapidly. Here, too, there is fundamental unity. Two quite different plants are basically the same.’ [Steiner, R. GA 216.]