Nuzzo, V. (Natural Area Consultants, 1 West Hill School Road, Richford, NY 13835). Demography and habitat of Corydalis flavula (Raf.) DC. (Fumariaceae) in south-western Michigan (U. S. A.). J. Torrey Bot. Soc. 132: 16–23. 2005.—Corydalis flavula (Raf.) DC. is a rare winter annual in Michigan, restricted to two counties in the southwestern portion of the state. Corydalis flavula density, capsule and seed production, and composition and structure of the associated groundlayer and overstory, were recorded 18–26 May 1998 in six 5,600 m² plots. Corydalis flavula plants were sparsely dispersed, averaging 1.4 plants/m² and 1.1% cover in all plots. Over 95% of C. flavula plants produced flowers, and 89% produced seeds. Flowering plants produced an average of 4.0 capsules, each with an average of 3.8 seeds, and seed production averaged 15.1 seeds/flowering plant, and 19.9 seeds/m². Over 11% of plants were browsed by deer, foliage on 3.4% of plants showed insect feeding damage, and 3.7% of capsules showed external attack. Inside capsules, insect attack was more frequent, averaging 11%. The six stands where C. flavula was monitored were relatively similar: young, second growth, disturbed forests, dominated by black locust (Robinia pseudoacacia L.) and subdominated by black cherry (Prunus serotina Ehrh.). Tree density ranged from approximately 750–1250 trees/ha, and dead trees were common, accounting for an additional 28% of all trees > 10 cm dbh. Corydalis flavula presence was associated with shorter groundlayer vegetation (25 cm vs 29 cm) and lower groundlayer cover (96% vs 107%), and abundance was significantly higher in both quadrats and plots with low graminoid cover and high annual and biennial cover. Corydalis flavula, like other woodland annuals, is disturbance adapted, and conditions that favor growth of woodland annuals also favor the growth of C. flavula.