Staminate Hop Plant
The flowers of hops are grown on different plants. Only the pistillate flower has value fro the standpoint of the hop grower; but it is supposed to be advantageous to have the flowers fertilized, and therefore is customary to grow staminate plants at regular intervals in the hop field. This picture, showing the staminate hop plant, may be contrasted with the succeeding one.
This image is from: Luther Burbank: his methods and discoveries and their practical application. Volume 8 Chapter 5