Journal Article

THE EFFECT OF HEIGHT AND SEED PROVENANCE ON EARLY FLOWERING IN BUR OAKS (QUERCUS MACROCARPA)

Garner, Mira, Krupa, Alex, Mohn, Rebekah A, Branz, Alison, Pearse, Ian S, Steele, Jonathan, Hipp, Andrew L, Lapadat, Cathleen, McCarthy, Heather R, Whittemore, Alan T, Bugnaski, Zoe, Cavender-Bares, Jeannine, Worcester, Lindsey, Rea, Lucy

2025

Overview

Bur oaks (Quercus macrocarpa) are long-lived trees that often require two to three decades to mature from seedlings. The rate at which they do so may depend on how rapidly they grow, as maturity is often correlated with height. Many woody monoecious species, like pines and birches, often produce only staminate flowers in their first year of maturity. Using our common garden of 600 bur oak trees from three states (Oklahoma, Illinois, and Minnesota), we asked how long it took for trees to reach maturity, whether maturity was correlated with height, and what types of flowers trees produced early in maturity. We found that 18% of trees flowered after six years of growth and 40% after seven years of growth. Within each population, height was positively correlated with flowering. However, the population with the tallest trees (Oklahoma) had the smallest percentage of trees flowering. Surprisingly, many of the trees produced only pistillate flowers. Our findings suggest that the relationship between maturity and height differs genetically in the Oklahoma population compared to the Illinois or Minnesota populations. Additionally, our finding that bur oaks from all three populations produced pistillate flowers prior to staminate flowers raises questions about the generality of trade-offs between resource availability and allocation to reproduction in flowering plants, in which pistillate flowers are generally assumed to be more costly.

• Publisher: Harvard University Herbaria
• Subject: Females / Flowering / Flowers & plants / Maturity / Quercus macrocarpa / Resource availability / Seeds / Trees