Table 1: Candidate examples of parallel ecological speciation in plants showing the strength of evidence for each case. The details of each example can be found in Appendix A. The strength of evidence for each case was coded as follows: ***: strong direct evidence, **: weak direct evidence, *: indirect evidence, —: no evidence, †: evidence against, and NA: no data.

Species Min. number of origins Independence Isolation Compatibility Selection Major parallel trait(s) References Alopecurus myosuroides LX Many ** NA NA *** Herbicide tolerance [45–51] Agrostis capillaries LX Many * * * ** Edaphic tolerance [52–54] Agrostis stolonifera LX NA NA * * ** Edaphic tolerance [55–57] Agrostis tenuis L NA * ** NA ** Edaphic tolerance [58, 59] Armeria maritima LX NA *** † * * Edaphic tolerance [60–63] Chaenactis spp. LX 2 *** † ** * Flower colour [64, 65] Cerastium alpinum 2 ** * NA *** Edaphic tolerance [66] Chenopodium album LX NA * NA NA * Herbicide Tolerance [67–70] Crepis tectorum LX 2 ** NA NA ** Leaf morphology [71, 72] Deschampsia caespitosa L 2 ** * * * Edaphic tolerance [73, 74] Eucalyptus globulus 3 *** ** * * Dwarfed morphology [75] Geonoma macrostachys 3 ** ** * * Habitat type; reproductive strategy [76–78] Hemerocallis citrina var. vespertina 3 ** * * NA Nocturnal flowering [79] Hieracium umbellatum LX NA * * * * Habitat type (dunes) [80] Lasthenia californica 2 *** ** ** ** Edaphic tolerance [81–87] Microseris lanceolata L 2 *** * ** * Habitat type (elevation) [88–90] Petunia axillaris 6 ** *** * — Flower colour [91, 92] Plantago maritima LX 2 * NA NA NA Spike morphology [93] Poa annua LX NA * — * * Herbicide tolerance [94, 95] Schizanthus grahamii 2 ** ** NA * Pollination syndrome, self-compatibility [96] Silene dioica LX NA ** NA NA — Edaphic tolerance [97, 98] Silene vulgaris LX 2 * * NA *** Edaphic tolerance [99–102] Streptanthus glandulosus Many ** * * ** Edaphic tolerance [103–107]

L: Levin example. X: Example that would not have been included in this table had they not been reviewed in Levin [12].