phytomerBot.|ˈfaɪtəʊmə(r), ˈfɪt-| [ad.mod.L. phytomeron, pl.-a, f.Gr. ϕυτό-ν plant + µέρος part.] = phyton. 1880Gray Struct.Bot. (ed. 6) 7 Phytomera,..equivalent to plant-parts... In English, the singular may be shortened to Phytomer.Ibid. 9 The plant begins as a single phytomer.