Figure 2
Morphology and structure of the dandelion seed unit. (a) Optical photo of a side view of a dandelion seed unit, consisting of the pappus–beak–achene with ∼113±11 pappi that are 5 mm in length. (b) The cartoon of the dandelion seed unit indicates that the open angle between each pappus, noted as 2β, is ∼160° to 180°. (c) Optical photo of a top view of a dandelion seed unit, with the pappi radially arranged on top of the beak to form an open radial system. (d) Scanning electron microscope (SEM) image of a single pappus revealing a conical structure with a length of ∼0.5 cm. (e) Magnified SEM images that taken from three different positions, the tip (e1), the middle (e2) and the bottom (e3) of the pappus. (f) SEM images of the sucker-like structure of the pulvinus (f1) with a protuberant closed circle in the middle (f2) and a radial distributed roughly textured surface on the surrounding area (f3).
