Final answer:
The genus Populus includes species like the Trembling Aspen (Populus tremuloides), which is widely distributed across North America and grows clonally. Phylogenetic studies have expanded the willow family, to which Populus belongs, from three to 56 genera. Populus species should not be confused with other trees like the tulip poplar or parasites such as the Birch polypore.
Step-by-step explanation:
The Populus genus includes about 25 species within the willow family and has a wide distribution in the northern hemisphere. One of the most commonly known species in North America is the Trembling Aspen, scientifically known as Populus tremuloides. This species is not only widespread across the continent, from Alaska to Mexico, but also has the notable characteristic of growing clonally, often forming monotypic stands. While cottonwoods such as Populus deltoides and Populus fremontii are frequently found along streams and rivers, aspens including Populus tremuloides and Populus grandidentata can be found in various upland habitats.
Phylogenetic studies using molecular information have significantly expanded our understanding of the willow family, increasing its size from three to 56 genera. Poplar species such as tulip poplar (Liriodendron), which has distinctive annual growth rings in its xylem, should not be confused with the genus Populus. Additionally, it is important to differentiate Populus species from others mentioned, such as the state tree of Pennsylvania, the Eastern hemlock, or parasites like the Birch polypore that primarily attack birch trees. The poplar tree in the image appears to be a Trembling Aspen (Populus tremuloides), which is one of the most widely distributed trees in North America. It can be found from the east coast to the west coast and from Alaska to Mexico. The genus Populus includes several other aspen species and cottonwoods, with a worldwide distribution in the northern hemisphere.