  We present low resolution (R~450) K-band spectroscopy for 16 of the 43
circumnuclear star-forming knots in M100 identified by Ryder & Knapen (1999).
We compare our measurements of equivalent widths for the Br-gamma emission line
and CO 2.29 micron absorption band in each knot with the predictions of
starburst models from the literature, and derive ages and burst parameters for
the knots. The majority of these knots are best explained by the result of
short, localised bursts of star formation between 8 and 10 Myr ago. By
examining both radial and azimuthal trends in the age distribution, we present
a case for sequential triggering of star formation, most likely due to the
action of a large-scale shock. In an appendix, we draw attention to the fact
that the growth in the CO spectroscopic index with decreasing temperature in
supergiant stars is not as regular as is commonly assumed.
