Adventives

Adventives are a term used in botany and ecology to refer to non-native plant species that occur in a region outside their native range and outside cultivation. The precise definition varies among authors; most commonly adventives are plants that have arrived by human activity or natural dispersal but do not yet form persistent, self-sustaining populations in the wild.

In practice some botanists broaden adventives to include all recent non-native occurrences in the wild, while others restrict the term to casual or transient occurrences that fail to establish over time.

Adventives contrast with native species and with naturalized or invasive aliens. Archaeophytes and neophytes are historical classifications based on the time of introduction rather than on persistence; adventives can overlap with neophytes when introductions are recent. A pivotal distinction is whether the species has established stable populations: naturalized species reproduce and maintain in the wild without cultivation; adventives may be observed sporadically and are often still dependent on cultivation or ongoing introduction.

Common pathways include escape from horticulture, seed pollution in trade or cultivation, shipping, and accidental introductions via contaminated goods or animals. Adventives may persist for short periods or recur in certain habitats, but their long-term status is uncertain; some may become naturalized or even invasive, while many remain rare or transient.

The concept and usage of adventive differ by region and discipline, leading to varying lists in flora inventories. For researchers and conservation practitioners, noting the adventive status helps assess introductions, potential ecological impacts, and management priorities.