"The ERDL pattern, also known as the Leaf pattern, is a camouflage pattern developed by the United States Army at its Engineer Research & Development Laboratories (ERDL) in 1948. It was not used until the Vietnam War, when it was issued to elite reconnaissance and special operations units beginning early 1967.
The pattern consists of four colors printed in an interlocking pattern. It was initially produced in a green-dominant colorway, consisting of large organic shapes in olive green and brown, black 'branches' and light green 'leaf highlights'. Shortly after it was first fielded in Vietnam a brown-dominant scheme with the light green replaced by light tan was introduced."
Source: Wikipedia
Additionally, this pattern was also used on uniforms worn by the United States Marine Corps in the mid to late 70s. This version was specifically known as the RDF (Rapid Deployment Force) cut of the uniform. Unlike the original models ERDL was printed on, which was printed on an OG-107 jungle fatigues cut, it was slightly different. Both chest pockets were oriented straight up and down, rather than tilted, looking extremely similar to the M81 BDU (Battle Dress Uniform) which would succeed it not long afterwards.