An official website of the United States government
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS
A lock (
LockA locked padlock
) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
Image Number K9966-1
Plant physiologist Chandra Holifield separates grass samples used to validate the SEHEM plant-growth model.
Photo by Peggy Greb.
640 pixels wide: (k9966-1.jpg)