Attaching mechanism of dandelion seeds: results from morphology/structure and abscission force/angle

Mature dandelion seeds can be easily abscised from their capitulum by a tiny vibration or a gentle wind, and the previous study has revealed their abscission mechanism, but the mechanism governing the attachment of immature dandelion seeds is still unclear. This paper aims to uncover the attaching mechanism by morphology/structure analysis and abscission force/angle measurement. Connecting region of the immature dandelion seeds consists of upper barbs from neighboring achenes, lower barbs of achene and their groove in capitulum. The upper barbs have hierarchical structures that form barb-barb interlock, the lower barbs and their groove produce barbs-groove wrapping, together endow the dandelion seeds with a firm attachment (abscission force >155.9 mN). The firm attachment weakens sharply with the growth of dandelion seeds, which attributes to the considerable changes in morphology/structure, showing the remarkable decrease of abscission angle (critical opened stage 37.1 ± 5.2°, full opened stage 11.6 ± 3.0°) and the tiny abscission force (10.67–0.35 mN). The results reveal the attaching mechanism of immature dandelion seeds, and may inspire some novel biomimetic designs for the controllable attachment/abscission materials.