Datura wrightii -- Sacred Datura -- Perennial with very large, sweetly night-scented white flowers. A scrambling spreader blooming from April to October, it is quite drought-tolerant, as befits a native of the dry west, California to Mexico. And as befits a plant that grows at altitudes to 6000', it is hardy at least to zone 8. A large, spreading plant that needs plenty of room, but very showy and useful for dry spots. All parts of the plant are very poisonous.

Derwentia perfoliata -- Diggers' Speedwell -- A crisis in taxonomic nomenclature is looming over this plant, which used to be called Veronica perfoliata. The British, who have the authority of a century devoted to importing and studying plants from around the world, have determined that it should now be named Parahebe. The upstart Australians, however, are determined to call it Derwentia. Just because it happens to grow there, they seem to think they should be able to name it. We Americans are staying carefully neutral, but worry about a conflict reminiscent of the Faulklands. Anyway, what do we know? When we first saw this plant, we were sure it was a Eucalyptus! It has the right bluegreen color and thick, leathery leaves, but turns out to have a definite prostrate, trailing habit with willowy stems that don't even think about growing upright. And then, in midsummer, sure enough, there are those elegant, long, branching sprays of violet blue Veronica, er, Parahebe, er, Derwentia flowers. Zone 8. We used to say zone 6, but wouldn't you know, there's an argument about that. For a change, maybe we'll just go with the uncontested common name, Digger's Speedwell.

 Dianella tasmanica -- Dianellas are Southern Hemisphere grasslike spreading perennials in the lily family, with narrow, glossy, straplike leaves. They produce blue flowers followed by ornamental blue berries. This plant grows to 4', with flat, not keeled, leaves that mainly emerge directly from the ground, but sometimes in fans on short stems. Flowers are lavender-blue to violet, with pale yellow anthers, and the ovoid berries are dark blue.

Dietes iridioides -- Fortnight Lily -- For years we've set up shop at one or another local farmers' market on Saturdays. In this situation, you always need an attention-grabber, something that will slow the customers down and make them give your booth a closer look. We have discovered over the years that blooming Dietes (dye EET ees) never fail to stop traffic. I'm not sure why, but for some reason these South African Iris-family corms get a second look from almost everybody. This low-growing form reaches about 18" with flowers that typically have white petals with yellow markings, with a light blue crest. Zone 9 in the ground, easily overwintered indoors. AKA D. vegeta. Flowers seem to come in 2-week waves, hence 'fortnight'.

Dovalis caffra -- Kei Apple is a spiny shrub or small tree bearing edible but acid fruit which is of some economic importance in arid countries. It is also often used as a bonsai subject in mild climates. In the ground, it will grow to about 15', with small, creamy-green flowers in summer, followed by large yellow-green fruits. It's notable spininess gives rise to its name, the Greek word for spear. It will survive temperatures of 20°F for short periods, but temperatures a few degrees lower have been fatal. From the Kei River area of the Eastern Cape , South Africa.

Drimiopsis maculata -- African Hosta -- A neat little low-growing bulbous plant from South Africa. Thick, wavy-margined 2x3" olive green leaves have very distinct, almost black leopard spots in profusion. White flowers are borne in tight spikes reaching 12". Usually grown as a houseplant in the north, but it seems fairly cold hardy here with a mulch, and one grower lists it as zone 7b. It has been called "African Hosta", but this seems a bit of a stretch. Leaf shape is similar, but much smaller, and Drimiopsis has an above-ground pseudobulb. It seems more similar to a squill (Scilla or Ledebouria). A prospect for that most difficult of growing situations, dry shade.