Many species of geophyte vascular plants are reported to remain dorman
t during the growing season. We examined data from our own and publish
ed studies and found that, generally, 25% or less of the plants in the
se populations demonstrated prolonged dormancy during any one year. In
dividual plants usually remained dormant for 1-2 years. Population est
imates of plants with prolonged dormancy based on random sampling meth
ods will often underestimate density. Permanent plot methods with repe
ated measures analysis can be used to monitor change in population den
sity with a reduced risk of bias. Demographic monitoring studies of sp
ecies with prolonged dormancy will require longer periods of time to o
btain useful information.