The writers are unfamiliar with basic chemistry. Moreover, one reason why agar is so useful in the bacteriological laboratory is that, by itself, it does not support the growth of heterotrophic organisms. Addison-Wesley's writers have got things exactly wrong. The second part is just an adjective that, by itself, is not the name of anything. The writers should have done some library work of their own, instead of guessing.
Red snow is caused by one of the green algae.
Page 199 says that the staminate flowers and the pistillate flowers of plums grow on different trees. This too is quite wrong. They are not representative dicots, and the whole business is misleading. Given the mislabeled picture, that question is meaningless. Moreover, the picture lacks any indication of the size or scale of the objects shown.