Scaling of Floral Display and Mechanical/Hydraulic Support Across Twelve Crabapple Cultivars

Flowers of the Rosaceae, with their distinct pedicels and well-differentiated floral organs, provide an ideal model for investigating biomass allocation trade-offs associated with the balance between reproductive investment and mechanical/hydraulic support. However, the scaling relationship between supportive structures (e.g., pedicels) and floral display structures (e.g., petals) remains largely unresolved. We examined 12 crabapple (Malus) cultivars, measuring their pedicel length, pedicel fresh mass, corolla fresh mass, corolla area, and total flower fresh mass. Scaling relationships among these traits were evaluated using reduced major axis regression protocols. Pedicel fresh mass increased disproportionately with increases in pedicel length, total flower fresh mass, and corolla fresh mass, indicating preferential biomass allocation toward structural and hydraulic support. The scaling exponent between fresh mass of floral organs excluding the corolla (FEC) and corolla fresh mass was lower than unity, suggesting preferential allocation toward floral display structures. Corolla area increased more slowly than corolla fresh mass but showed an approximately isometric relationship with total flower fresh mass, revealing distinct scaling patterns between floral display area and biomass investment. This study provides a cultivar-level perspective on floral support-display coordination, advancing our understanding of reproductive strategies in angiosperms.