Monocots and eudicots have more conservative flower water use strategies than basal angiosperms

Water balance is crucial for the growth and flowering of plants. However, the mechanisms by which flowers maintain water balance are poorly understood across different angiosperm branches. Here, we investigated 30 floral hydraulic and economics traits in 24 species from ANA grade, magnoliids, monocots, and eudicots. We found that basal angiosperms had richer petal stomatal density, higher pedicel hydraulic diameter, and flower mass per area, but lower pedicel vessel wall reinforcement, and epidermal cell thickness, compared to monocots and eudicots. This indicates that basal angiosperms maintain water balance with high water supply and consumption, while monocots and eudicots maintain water balance more conservatively. We also observed significant trade-offs and coordination among different floral traits. Specifically, pedicel theoretical hydraulic conductivity was positively correlated with petal stomatal density, flower water potential at turgor loss point, and maximum vessel diameter...