Gibberellic Acid: An Unusual Plant-Regulating Chemical. E-book. Formato PDF United States Department Of Agriculture   -  Forgotten Books, 2017  - 

Gibberellic acid is a chemical which can change plant growth and develop ment in varied ways, suggesting agricultural uses. It is a natural product of an Asian fungus.

The Periodical Cicada / The 17-year Locust: (Illustrated Edition). E-book. Formato PDF United States Department Of Agriculture   -  Ionlineshopping.Com, 2019  - 

No other insect in North America excites as much curiosity and wonder as does the periodical cicada when it makes its sudden, springtime appearance at intervals of 17 or 13 years. After years of living in underground tunnels, millions of cicadas issue from the earth as if by a predetermined signal, undergo startling transformations, and spread through nearby trees and bushes. From morning till night they fill the air with their weird, droning song. In a few weeks, after mating and laying eggs, they die. The periodical cicada, often erroneously called the 17-year locust, is widely distributed over the eastern half of the United States, and occurs nowhere else in the world. In the North its life cycle is completed in 17 years; in the South the cycle is completed in 13 years.