Original 1st printing 14 x 20&1/2" concert poster for the Youngbloods appearing with Wildflower, Magic Fern and "Chapter 3 of the Junior G-Men" at California Hall in San Francisco, CA from 7/21-22/1967.
Art by Greg Irons, image ("Strange Happenings") is featured in the Art of Rock on page 174 (plate 2.140).
Medium flat vellum stock poster is in good (B) condition; there are a pair of small wedge tears in the lower left/top right corners, a few stray handling dings, a pair of tiny drip stains in the upper left corner, light handling, a few small edge bends here and there and a set of tape pulls on the reverse, otherwise fine.
An overall very-decent-looking example of this somewhat hard-to-find Greg Irons image from the Art of Rock with strong colors and a classic Marvel Comics-inspired design.