Betula pumila is a deciduous

Deciduous

Deciduous means "falling off at maturity" or "tending to fall off", and is typically used in reference to trees or shrubs that lose their leaves seasonally, and to the shedding of other plant structures such as petals after flowering or fruit when ripe...

 shrub

Shrub

A shrub or bush is distinguished from a tree by its multiple stems and shorter height, usually under 5–6 m tall. A large number of plants may become either shrubs or trees, depending on the growing conditions they experience...

 native to North America. It reaches 1-4 meters in height. Its reproductive structures are catkins similar to other birches.

Its twigs develop on spur shoots. Leaves are alternate but close together, especially on slow growing individuals. Leaves are coarsely dentate and rounded at the base.