8 
PLANTS OP YELLOWSTONE NATIONAL PARK 
every time we wished to learn the name of a plant, identification 
would be difficult. Therefore, a key has been prepared to aid us 
in finding the correct names of the plants in which we are interested. 
With a little practice in the use of this key, we should be able to name 
correctly any wild flower or tree that we find in the park. We shall 
find that at each step in the key we shall have two or more alterna¬ 
tives to choose from, and we must decide which alternative fits the 
plant that we have in hand. If we make the correct decision in each 
case, we shall find the correct name of the plant, and the correctness 
of our decisions will depend upon the accuracy of our observations. 
Therefore, we must learn to make accurate observations. 
In order to see just how the key is to be used, let us take an 
example. Let us suppose that on one of our walks in the park we 
find some plants about 10 inches high with opposite, entire leaves 
and blue flowers. We stoop down to examine one of the flowers 
more closely, and we find that the corolla consists of a regular, 
4-lobed tube, and that there are 4 stamens and 1 pistil with the stigma 
or upper end of the style divided into 2 parts. We are now ready 
to use the key. 
Turning to the beginning of the key on page 12 we find we are 
confronted at once with two alternatives, both numbered 1. These 
are: “ Plants without seeds or true flowers. Spore producing ” and, 
“ Seed-producing plants.” Our plant has flowers and so is obviously 
a seed-producing plant. Therefore, we will choose the second alter¬ 
native. This is followed by the figure 5, which means that 5 is our 
next step in the key and we can skip 2, 3, and 4. At 5 we again have 
two alternatives: “Woody plants (trees and shrubs)” and, “ Non- 
woody plants.” Since our plant is not at all woody, we again choose 
the second alternative and our next indicated step is 44. At 44 we 
choose the second alternative, “ Plants with green leaves ”, and pass 
on to 50. In a similar manner we pass successively to 61, 62, 67, 69, 
72, 80, 88, 89, 90, 91 (where we find three alternatives), and 92, choos¬ 
ing, in each case, the alternative that fits the plant in which we are 
interested. At 92 we find that the alternatives are: “Style branches 
2 ” and “ Style branches 3.” We have already observed that 
the style of our plant has two branches, so we will choose the first 
alternative. This we find is not followed by another key number but 
by the name “ Gentian ( Gentiana ) ” and “ p. 100.” This means that if 
we have not made any mistake our plant is a gentian and is described 
on page 100. We will, therefore, turn to page 100. Here we will find 
several species of gentian described, and by reading these descrip¬ 
tions we will readily conclude that our plant is the Rocky Mountain 
fringed gentian (Gentiana elegans). 
