Adventive plant

Many alien plants have been introduced to aesthetically improve public recreation areas or private properties, or for agricultural purposes.

Though the word has different shades of meaning, as it is also used for species that settle into new environments, and are not self-sufficient or are rarely naturalized, but need an episodic population assistance from their homeland.

[8] Depending on the question and perspective, adventitious plants are divided into different subcategories: The year 1492 is a conventionally chosen reference point.

Adventive plants are often found at freight stations, along railway lines and port areas as well as airports, but also on roads.

Occasionally, seed contamination also introduces new plants that could reproduce for a short period of time (so-called speirochory).

Though an alien, its leaves attract insects which serve as a food source for populations of native birds.

[16] Alien species have been observed to undergo rapid evolutionary change to adapt to their new environments, with changes in plant height, size, leaf shape, dispersal ability, reproductive output, vegetative reproduction ability, level of dependence on the mycorrhizal network, and level of phenotype plasticity appearing on timescales of decades to centuries.

A number of fast spreading, alien plants such as kudzu have been introduced as a means of erosion control.

This involves the purposeful introduction of a natural enemy of the target species with the intention of reducing its numbers or controlling its spread.

[20] Another troublesome alien species is the Phyla canescens, which was intentionally introduced into many countries in North America, Europe, and Africa as an ornamental plant.

[21] A form of unintentional alien introduction is when an intentionally introduced plant carries a parasite or herbivore with it.