The 15 species of Datura have fragrant, spectacular trumpet shaped blooms on bushy plants to 5m high. All parts of the plant are toxic, but reported cases of poisoning are rare as stems and leaves are furry and flowers contain a bitter juice. Grow in sun or part shade in most soils. They are frost tender and damaged by extreme winds but hardy to moderate drought.
Dianthus deltoides (maiden pink) and D. barbatus (sweet william) are cottage garden classics that revel in sun, warmth and well drained if not droughty conditions provided the soil doesn't completely dry out. Excellent for rockeries, the border garden, along gravel paths and in containers. The spicy, fragrant flowers are superb of picking. Easily grown.
Dietes, the Wild Iris, is a South African native with sword-like, evergreen leaves topped by 60cm flower spikes in spring to summer. These resemble the iris in yellow and brown shades. D. vegeta and D. grandiflora have exquisite large white blooms blushed with mauve against yellow-orange markings. Beautiful near ponds and banks but quite drought hardy for the partly sunny rockery, under trees in a drier spot or in containers.
Dimorphotheca, the Star of the Veldt or African Daisy, is a hardy, very drought resistant perennial with large white, pink or purple flowers over deep evergreen foliage. D. aurantiaca is an annual species in yellow, orange, apricot and cream. All are excellent for bedding, banks and containers and the coast in hot, dry sunny spots. Plant seed or cuttings now onward but shelter seedlings from freezing and cold, wet conditions.
Dorotheanthus, the Livingstone Daisy, is an annual succulent "ice plant" that puts on a magnificent display of brilliantly coloured daisy flowers with pale centres and a red eye. Plant the seed or seedlings now through spring in a sheltered, well-drained, sunny spot. Great on banks, paths, containers, and by the coast. Very drought tolerant but don't overwater!
Drosanthemum, the Redondo Creeper, is a close relative with the smallest flowers of any ice plant and the loveliest show. The dense carpet of fine, grey green, succulent foliage is completely smothered in spring with mauve, red, pink or white blooms that can cascade for meters off walls and down banks. There's almost no maintenance to this one and it is easily started from cuttings. Avoid walking on the succulent stems.
Dracaena draco, the Dragon Tree, gets it's name from the red sap that exudes from the stem when cut. In it's native Canary Island home it was thought this sap was dragon's blood with rare healing properties. They resemble thick-leaved cabbage trees when juvenile but soon branch to make gnarled, unique trunks that divide and subdivide to create spreading mushrooms crowned with fleshy rosettes or sword-like leaves. Excellent in containers when young and incredibly durable to everything except freezing and overwatering.
For the driest spots try Dryandra polycephala, a Western Australian protea with golden flowers that dry "forever".
A hot, sunny site and sandy soil are essential for success.