Ecotypic Differentiation in Ohio & Mississippi Populations of Acer Negundo L.

Laboratory investigations of Acer negundo populations from two widely separated habitats revealed distinct patterns of ecotypic differentiation in budbursting, leaf fall, and chlorophyll levels. Second year seedlings of Mississippi seed origin had complete leaf emergence before any evidence of budbursting in the Ohio progeny of similar age. Leaf fall patterns showed a clear difference between the two populations with Ohio plants dropping their leaves 2.5 weeks prior to complete defoliation in the Mississippi progeny. Significant differences in chlorophyll levels were demonstrated with the more northern (higher latitude) Ohio population showing consistently greater amounts of chlorophyll per gram dry weight than the more southern (lower latitude) Mississippi population. The chlorophyll differences were consistent as the individual plants aged during the investigation and were also found in comparing first and second year old seedlings. Examinations at the ultrastructural level revealed significant differences in the number of starch grains per cell section with higher averages in the Ohio population. No significant differences were found between the two populations in wood specific gravity