Invasive species: What are they?
In Rhode Island, nearly 400 plants are considered to be naturalized. In other words, they were introduced from other sources (mostly foreign) and are capable of reproducing and spreading without the aid of human assistance. Of this group, only about 30 are considered invasive because they have the potential for rapid and wide-spread dispersal and establishment, often at the expense of native plants. In general, invasive species share several key characteristics:
They produce an abundance of fruit and seeds.
They have short juvenile periods, usually less than 5 years.
Seeds are readily consumed and dispersed by animals, especially birds that "introduce"
the plant to new sites far from the source population.
They also reproduce and spread vegetatively by rhizomes or suckers, resulting
in dense stands.
They have long flowering and fruiting periods.
They have no special seed germination requirements, such as a cold period. They
have few natural predators or diseases in North America to keep them under control.
---Richard Enser