Black alder, Alnus glutinosa, represented by 28 seed sources from various natural and planted stands, was studied for six years in the coastal plain of Maryland. Also included were one source of each, A. incana and A. cordata. Different populations of A. glutinosa ranged in survival from 58% to 100%, height from 3.4 m to 6.6 m, advance of flushing leaves (on April 23, 1984) from none to fully developed, infestation by the aphid,
Prociphilus tesselatus, on 0% to 37% of trees, developing of female flowers during the 4th and 5th growing seasons on 0% to 92% of trees, and producing male flowers during the 5th season on 0% to 100% of trees. A. glutinosa included five populations that were 10% to 18% taller than average.
The most noteworthy correlations in Alnus glutinosa were the earliness of leaf flush vs. the northern latitude (r=–0.59) and vs. the eastern longitude of the seed source (r=–0.62). Also correlated were the survival rates vs. one-year heights (r=0.54), the aphid infestation vs. altitude of the seed source (r=0.36), and early flower production vs. six-year height (r=0.35 to 0.54). Alnus cordata grew 11% taller than A. incana, and both these species were about average in comparison to A. glutinosa.