a–f, The five most abundant grass taxa (expressed as proportion of total reads) are depicted alongside the total proportion of reads assigned to family Poaceae using the markers ITS2 (left) and rbcL (right). a, Bangor. b, Exeter. c, Invergowrie. d, Isle of Wight. e, Worcester. f, York. Owing to errors in sampling equipment, only four alternate weeks (out of a possible seven alternate weeks) of samples were collected at the York sampling site. A map of sampling locations and daily Poaceae pollen concentrations can be found in Fig. 1.