Delphinium is a large genus in the buttercup family, Ranunculaceae, with around 300 species. Most are tall perennials with a distribution in temperate regions of the northern hemisphere, reaching south to mountainous areas in Africa. Garden cultivars are numerous and more widely grown in gardens than the species.
Dianthus is a large genus in the family Caryophyllaceae, with around 300 species. The majority are distributed around the Mediterranean, reaching north into Europe and east to Asia. Most are mat forming plants that grow best in dry, gritty soil in full sun and are therefore well suited for rock gardens.
Dicentra is a small genus in the poppy family, Papaveraceae with 8 species native to N-America and E-Asia. They have finely divided leaves and irregularly shaped flowers, often heart shaped. They grow in sun or semi-shade in fertile soil. A few species formerly classified in the Dicentra genus have been moved to four other genera, among them is Dicentra spectabilis, which is now the only species in the genus Lamprocapnos.
Digitalis - Foxglove
Digitalis, is a genus of around 20 species in the family Plantaginaceae. They are tall plants with long flower spikes and a basal rosette of leaves. They are very poisonous. They are distributed around W- and SW-Europe, W- and Central Asia, Oceania and NW-Africa.
Dodecatheon is a small genus of similar species in the primrose family, Primulaceae, closely related to primroses, Primula. The species are all very similar and difficult to identify. All are native to N-America and some also to NE-Asia. They have a basal clump of leaves and the flowers have distinctive sepals that are twisted backwards. They need moist, fertile soil and can tolerate some shade.
Dracocephalum - Dragonheads
Dracocephalum is a genus of about 60-70 species in the Lamiaceae family. The majority of species are native to Central-Europe and N-Asia. The species commonly grown in Iceland grow best in dry, poor soils in full sun.