Fig. 243. Tea grades.

a. Flowery Pekoe.
b. Orange Pekoe.
c. Pekoe.
d. Souchong 1st.
e. Souchong 2nd.
f. Congou.
a, b. (When mixed together) Pekoe.
a, b, c, d, e. (When mixed together) Pekoe Souchong.
If there be another leaf below f, and it be taken, it is named and would make Bohea.
Each of these leaves was first a flowery Pekoe leaf (a), it then became b, then c, and so on.
At the base of the leaves c, d, e, f, exists buds 1, 2, 3, 4, from which new shoots spring.

This image is from Tea in King's American Dispensatory, 1898.