Silver (warty) Birch (Betula pendula), fam. Betulaceae.
The forest trees are widely used to get the sap, "birch juice". Though it is thought that this procedure harms the tree, this species is not rare in our forest (in particular, it is quickly spreading on the fellings), so this practice is relatively safe for the nature. The nutritional and medicinal properties of the sap should not be overestimated; it has just a bit of taste, but anyway is better that the filtered water or other common beverages. The sap could not be stored fresh.
The young leaves are edible (though somewhat bitter and sticky, but with a pleasant flavor). The buds and the newly sprung leaves have strong antibacterial, antiparasitic, diuretic properties. Most often, the leaves are used for decoction, and the buds - for the alcohol tincture. Other parts of the plant are also used: catkins, bark, the tar made from that bark, and a rare mushroom called Chaga (Inonotus obliquus), parasitically growing on the trunks (not found in Kyiv).
The birch seeds remain in the catkin-like compound fruits until winter, when they begin to disperse intensively, accumulating in hollows of the snow (for example, in the man's footprints). The winter is a hard time for birches, because often they cannot bear adhering snow and strong winds, bend down and remain in this position forever.