This reminds me of a bush I know of as Breynia, but it does not become as woody and large as does Breynia. The plant of this sighting has slightly elliptical leaves and a thin dark red central stem (photo 4), and develops round seeds (photos 1 & 2), from what appear to be miniscule white flowers (photo 2). Photos 3 & 4 portray a typical looking cluster of these plants which self-seed readily even when very young and small.