The International Daffodil Register and Classified List (1998)
Horticultural classification
Section Jonquilla
Spring flowering; one to five (rarely eight) flowers to a rounded stem; leaves narrow or semi-cylindrical, green; flowers yellow, never white; perianth segments spreading or reflexed; corona usually cup-shaped, usually wider than long; anthers included in or partly exserted from the tube, much longer than the filaments, dorsifixed; flowers fragrant. The Autumn flowering, green-flowered N. viridiflorus is atypical
Section Apodanthi
Spring flowering; one flower or two to five to a somewhat compressed stem; leaves narrow, channelled, glaucous; flowers white or yellow, never bicoloured; perianth segments spreading or slightly reflexed; corona cup-shaped, funnel-shaped or flared, usually wider than long; anthers included in the tube or three included and three exserted, much longer than the filaments, dorsifixed
Section Ganymedes
Spring flowering; one flower or two to six to an elliptical or cylindrical stem; flowers pendent, white or yellow or somewhat bicoloured; leaves flat or semi-cylindrical; perianth segments reflexed; corona cup-shaped (rarely campanulate); anthers three included in the tube, three exserted (often beyond the corona), equal to or much shorter than the filaments, dorsifixed. Section covers N. triandrus
Section Bulbocodium
Autumn to Spring flowering; one flower to a rounded stem; leaves narrow, semi-cylindrical; flowers white or yellow; perianth segments insignificant compared with the dominant corona; anthers widely exserted from the tube (often beyond the corona), much shorter than the filaments (which are usually curved), dorsifixed
Section Pseudonarcissus
Spring flowering; usually one flower to a more or less compressed or sometimes rounded stem; leaves flat or channelled, usually glaucous; flowers white, yellow or bicoloured; perianth segments usually spreading or inflexed; corona more or less cylindrical, often flared at mouth, yellow or white (never orange or red); anthers exserted from the tube, equal to or shorter than the filaments, sub-basifixed. The green leaves, rounded stem and strongly reflexed perianth segments of N. cyclamineus and the two to four flowers to a stem of N. longispathus and N. nevadensis are atypical
NOTE: Hybrids distinguished solely by botanical name are also assigned to this Division