Is a sequoia tree perennial plant?

Yes, any plant that has a life cycle longer than two years would be considered a perennial plant, although the term is more often used in reference to herbaceous (soft stemmed) plants than to woody plants.

A plant that lives only a single year is called an annual - a bean plant for instance, which must be replanted from seed each year.

A plant that grows and vegetates in the first year, then flowers, seeds and dies in the second year (such as the carrot plant) is called a biennial or biannual.

A plant that continues to grow and produce seeds year after year is called a perennial.