The use of keys for Identifying plants and animals dates back many years. The addition of pictures to supplement the keys is more recent and makes their meaning clearer. The use of keys is much like traveling a strange region where the road intersections are well marked. If the traveller reads the signs intelligently and follows their instructions, he should have no trouble. A little understanding of terms and the use of care in selecting the right direction each time should find the correct family to which the plant belongs.

   It will be noted that the key statements are set in opposing pairs which are numbered alike but lettered differently. We find a toadstool in our front yard and wish to know to what family It belongs. With specimen at hand we start at page 10 and compare la with lb. Noting that our specimen has no flowers, true roots, or leaves, we try "Division Thallophyta, p. 10".

   This time we find three statements to be compared (la, lb, and lc); lb fitting the case shows us our specimen belongs to the Fungi on page 47 and we compare la and lb to select lb and go as directed to number 2 where 2b is seen to be right and we then consider 21 to seect 21b and then 22b, 60b, 64b, 65b, 67b successively. Finally 69b reveals that our specimen belongs to the "Family Agaricaceae". Now if we will go back through the keys noting the facts that lead us to our decision, we will have a good technical description of the Agaric mushrooms.

   Near our toadstool may grow a dandelion and we wonder about its family. Beginning again at page 10, lb, 2b, and 3b send us to the seed bearing plants, page 89, where it is found to be an Angiosperm (lb) and a Dicotyledon (4b). On page 100 we select lb then go in turn to 25b, 105b, and 106a to learn that the pesky dandelion is associated with the asters, daisies, and sunflowers in the great family Composltae.

   In the back of the book we find that a list of the families of plants arranged according to their relationship begins at page 151. If each plant studied is checked in this list and its relatives noted, the student will get a better concept of the plant kingdom, as well as having a graphic record of his progress.