Leucojum vernum (Spring snowflake) normally grows 15-20 cm tall (6-8 in), though it may reach up to 35 cm (14 in).
Leucojum aestivum (Summer snowflake) has a wider natural range, taking in Europe (including the British Isles), southwest Asia and northern Iran, and growing in wetter habitats including damp woodland, riversides and swamps.