Hemlock (Conium maculatum), fam. Apiaceae.
Widespread in the Southern part of Ukraine. Prefers humid, warm, and sunny places, where it can form giant thicket of 1.5-2 m height (the first photo). It is often said that hemlock has a "mouse smell". But those people forget that it has long ago become a norm for a modern man not to know what it means. Thus, other comparisons are needed - with the smell of a dirty dog or other animal. This suffocating odor is especially strong during the flowering. It warns about the toxicity of the plant, which is known since ancient times as a source of a poisonous alkaloid coniine. For instance, the historians think that it was this poison that Socrates had been killed with.
As for our forest, we also can sometimes meet the plants quite similar to Hemlock - along the roads, in shady, but relatively dry places. However, it might be other, harmless plant from the Apiaceae (Celery) family - for example, Cow Parsley - it is not sure. Anyway, there are no analogous thichets of hemlock around Kyiv.