It has been shown that a resonance of the reed contributes significantly to the playing behavior of the single-reed woodwind [S. C. Thompson, J. Acoust. Soc. Am. 66, 1299--1307 (1979)]. As an extended object, the reed is actually expected to possess many resonances, and these have been predicted in FEA calculations [D. Casadonte, J. Acoust. Soc. Am. 94, 1807(A) (1993)] and observed in vibration spectra of isolated reeds [D. H. Keefe and S. Waeffler, J. Acoust. Soc. Am. 94, 1833--1834(A) (1993)]. The current study used holographic interferometry to identify the vibration patterns of a clarinet reed mounted on a mouthpiece, as driven by an acoustic field internal to the mouthpiece. Without a player's lips to shorten the vibrating section, the lowest frequency and most easily driven resonance is in the region 1500 to 2000 Hz and corresponds to the lowest mode of a rod clamped at one end. The second and third resonances are near 4000 Hz. The second mode displays twisting motion, but with a surprising degree of asymmetry, while the third mode is similar to the second mode of a rod clamped at one end.