longissima has two distinct varieties: longissima var. longissima (identical to longissima var. brevifolia) is distinct from the very narrow-leaved longissima var. longifolia in having shorter leaves that show a distinct petiole transition. longissima var. longifolia has very narrow leaves that are strap-shaped and no leaf to petiole transition. The latter is rare in cultivation. This species is broadly related to sieboldii, so some similarities exist between the two.