Appendix 1.

Voucher and location information for Rumex bucephalophorus populations used in this study. All vouchers were deposited in the herbarium of the Universidad de Sevilla (SEV), Seville, Spain.

Voucher no.	Taxon	Locality	Geographic coordinates	Altitude (m a.s.l.)
SEV279249–279254	R. bucephalophorus subsp. bucephalophorus	Greece: Crete, Genari	38°21′66″N, 24°20′32″E	1
SEV249375–249376	R. bucephalophorus subsp. canariensis var. canariensis	Spain: Tenerife, Icod de los Vinos	28°21′31″N, 16°42′47″W	447
SEV285642	R. bucephalophorus subsp. canariensis var. fruticescens	Portugal: Madeira, between Poiso and Pico de Arieiro	32°43′58.31″N, 16°55′47.46″W	1500
SEV275565–275567	R. bucephalophorus subsp. hispanicus	Portugal: Azores, Terceira, Porto Judeu	38°38′53″N, 27°08′36″W	50
SEV285914	R. bucephalophorus subsp. gallicus var. gallicus	France: Les Mayons, Réserve Naturelle Plaine des Maures	43°20′32.34″N, 6°23′46.58″E	95
SEV285913	R. bucephalophorus subsp. gallicus var. subaegaeus	Spain: Huelva, Almonte, Doñana	37°7′48.44″N, 6°31′30.34″W	12