• The sepals, petals, and labella of flower across 26 Dendrobium germplasms exhibit varying degrees of heterogeneity in anatomical traits and physiological responses. • Flowers whose sepals, petals, and labella exhibit higher heterogeneity in biomass investment have shorter flower lifespans. • Increased structural trait heterogeneity was associated with reduced flower hydraulic failure resistance. • Water-related processes show a trend of positively correlated variation among sepals, petals, and labella. • Floral water storage coordinated with transport at whole-flower and individual perianth levels. Flowers of Orchidaceae exhibit morphological and functional heterogeneity in their perianth segments, with one petal specialized into a labellum, which serves as the core organ for insect-mediated pollination, and sepals have evolved petal-like traits that serve dual purposes, namely protecting the flower during its developmental stage and aiding pollinator attraction after blooming. While the floral arrangement in the attractive orchid goes this way, there has always been a paucity of information on the anatomy and physiological response underlying the morphological differences among these three perianth types. To address this research deficiency, we monitored the anatomical and physiological heterogeneity of three types of perianth. Further, we analyzed the relationships between such heterogeneity and key floral economically floral hydraulic balance traits across 26 Dendrobium germplasms. We found that flower lifespan was negatively correlated with the heterogeneity in biomass allocation across the three perianth types, and as the incrementing structural complexity increases, the heterogeneity of the floral parts elevates the risk of hydraulic failure. Notably, most water-related processes exhibited coordinated changes across the perianth types, and floral water storage was tightly coordinated with water transport as held at both the whole-flower and individual perianth levels. For multifunctional floral veins, sepals had higher major vein density, while labella exhibited the highest open vein density, which well links the protective function of sepals to the display function and potential secretory function of labella. This study enhances global Dendrobium horticultural diversity, deepens understanding of floral adaptive mechanisms, and supports conservation.
Peng et al. (Sun,) studied this question.