Mimulus guttatus x luteus (M. x robertsii)
A perennial hybrid of damp and wet places, including on mud and shingle by streams and rivers, in flushes and in marshy ground. This hybrid is partially fertile, and can spread vegetatively from stem fragments. It ascends to over 440 m above Garrigill (Cumberland) and probably to 610 m in the Ochils (W. Perth).
M. x robertsii was first recognised in Britain by Roberts (1964) but not named as M. x robertsii until 1990. The earliest record traced dates to 1872 (Berwicks.). It is the commonest taxon of high ground, and many records of Mimulus agg., M. luteus, and even M. guttatus are probably referable to this hybrid, which is therefore likely to be under-recorded.
A hybrid of garden origin.
PLANTATT - Attributes of British and Irish plants. (.zip 1455KB) This dataset was compiled and published in 2004, and last updated in November 2008. Download includes an Excel spreadsheet of the attributes, and a PDF explaining the background and nomenclature. Note that the PDF version is the booklet as published, whereas the Excel spreadsheet incorporates subsequent corrections. A hardcopy can be purchased from the Centre for Ecology and Hydrology.