Primary root growth in seedlings of the Hylocereeae tribe (Cactoideae), and Opuntioideae, Maihuenioideae and Pereskioideae subfamilies. (A–C) The primary roots of all developed seedlings of Epiphyllum phyllantus, which belongs to the Hylocereeae tribe from the Cactoideae family, exhibited indeterminate root growth. (D–G) The primary roots of Opuntia puberula, Opuntioideae, seedlings exhibited determinate growth (E), indeterminate growth (D, F) or failed to develop at all (G). The primary root of most Maihuenia patagonica, Maihuenioideae, seedlings (H–K) and of all Pereskia aculeata, Pereskioideae (L, M) seedlings exhibited indeterminate growth. (I) Some Maihuenia patagonica seedlings exhibited determinate primary root growth. (A) Two dpg; (B) same seedling as in (A), 4 dpg; (C) 20 dpg; (D) 3 dpg; (E) 10 dpg; (F) 10 dpg; (G) 10 dpg; (H) 1 dpg; (I) 2 dpg; (J) same seedling as in (H), 2 dpg; (K) 20 dpg; (L) 3 dpg; (M) 14 dpg. Scale bars: (A, B) = 2 mm, (D, G–J, L) = 5 mm, and (C, E, F, K, M) = 10 mm.