Late-discovered petaloid monocotyledons: separating the native and alien flora

Abstract

The criteria that might help in assessing native or alien status are set out and any recent developments noted. The major change has been a better understanding of north-western European distribution and alien plant occurrences, mainly through the production of dot-map floras. Six petaloid monocotyledons are examined — all well-known and long-grown garden plants, and all with not only a late discovery, but also with a subsequent almost immediate clumping of records from a number of counties. This is contrasted with the discovery and traits of species of similar broad habitats in the same counties, which were almost entirely found much earlier. Two probably alien species, Leucojum aestivum and Muscari neglectum, are examined in depth, and the history of their discovery contrasted with a certainly native third, Allium schoenoprasum. The advantages and disadvantages of using just the first date of discovery as a criterion for native or alien status are noted, as well as the perceived lack of any change in public attitudes towards alien plants. A significant improvement in the numbers of species covered in popular, keyed, floras, since 1990 has led, in turn, to a rapid increase in the number of recorders dealing with them and an equally rapid increase in records. This has complicated our understanding of the perceived threat to the native flora from alien species. Progress in Europe is noted and it is questioned whether there is the same concern there with the assignment of species to native and alien categories.

Keywords:

• Discovery
• Distribution
• Europe
• Garden plants

I especially acknowledge the input of Chris Preston and Kevin Walker, and also Mick Crawley, Stephen Evans, Mark Gurney, John Richards and Jane Stevens. I am grateful to Dr E. Welk, AGChorology, Institute for Biology/Geobotany Halle, Germany, for permission to reproduce his distribution map of Leucojum aestivum. I am grateful too for the very helpful comments of the reviewers.