Attaching 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 a previous study 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 morphological/structural analysis and abscission force/angle measurement. The connecting region of immature dandelion seeds consists of upper barbs from neighboring achenes, the lower barbs of the achene and their groove in the capitulum. The upper barbs have hierarchical structures that form barb-barb interlocks, and the lower barbs and their groove produce barbs-groove wrapping, together endowing dandelion seeds with a firm attachment (abscission force >155.9 mN). The firm attachment weakens sharply with the growth of dandelion seeds, which is attributed to the considerable changes in morphology/structure, showing a remarkable decrease in abscission angle (critical opened stage 37.1 +/- 5.2 degrees, fully opened stage 11.6 +/- 3.0 degrees) and a 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 controllable attachment/abscission materials.