Abstract Detail



Anatomy and Morphology

Kluck, Johanna [1], Jones, Teylor [1], Schmitz, Hailey [1], Gerken Golay, Michaeleen [2].

Seasonal Variation of Leaf Morphology in Hydrophyllum virginianum.

The herbaceous layer of a deciduous forest varies throughout the growing season, with certain plants photosynthetically active in different months. Hydrophyllum virginianum (Virginia waterleaf) flowers in spring but also produces new leaves later in the season, remaining active long after tree leaf drop. In early spring, H. virginianum produces a set of leaves that are often highly variegated (white spots resembling drops of water).  Later leaves do not show the same variegation. This pilot study was designed to characterize leaf morphology throughout the growing season, and determine whether chlorophyll a/b content and stomatal density likewise vary in spring, summer, and fall. Additionally, we calculated the proportion of each leaf that was variegated each month from May through October in a population of H. virginianum in a hardwood forest in northeast Iowa.  Forty individual plants were monitored biweekly to track leaf emergence and senescence. Monthly, one proxy leaf for each plant was harvested from the surrounding population for lab analyses of chlorophyll a/b ratios, stomatal density, and quantification of proportion variegated. Data were analyzed with ANOVA and Tukey post hoc. Results indicate that as expected, variegation was higher in spring. Stomatal density was highest in early leaves, intermediate in mid-season leaves, and lowest in late season leaves (p<0.0001).  Average chlorophyll a/b ratio did not differ between early and mid-season leaves (p=0.1091) but analyses by month revealed that chlorophyll a/b ratio is variable throughout the growing season (p<0.0001). Month-to-month fluctuation in leaf metrics did not follow the seasonal arc of tree canopy closure and senescence, which suggests that there may be a more complex interaction of environmental variables. As this was a pilot study, methods have been refined and monitoring and analyses are ongoing to further elucidate patterns.


1 - Wartburg College, 100 Wartburg Blvd, Waverly, Iowa, 50677, United States
2 - Wartburg College, Biology, 100 Wartburg Blvd, Waverly, IA, 50677, United States

Keywords:
herbaceous perennial
forest
seasonal.

Presentation Type: Poster
Number: PAM006
Abstract ID:277
Candidate for Awards:Developmental and Structural Section best poster


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