Sarcococca ruscifolia -- Sweet Box -- Dense, bushy evergreen shrub with small, glossy leaves and clusters of faintly vanilla-scented white flowers in winter or very early spring, followed in time by blue-black fruits. Useful as a groundcover or low hedge, growing very slowly to perhaps 5', but usually kept smaller by occasional pruning. A lover of part to full shade, it is sometimes used in that most difficult of conditions, dry shade, though it will tolerate full sun if the ground is kept moist. Resists insect, bacterial, and fungal pests, so is mainly care-free, except for pruning, if desired. Fragrant blooms in winter, ability to bloom in shade, ease of culture, and small size make this a very deisrable, though slow-growing, shrub. China and the Himalayas. Zones 8.

Schotia brachypetala -- Tree Fuchsia -- Large, semi-deciduous shrub or wide-spreading tree bearing bronze leaves and 1" long crimson flowers with an abundance of nectar for attracting, in Mozambique, Sunbirds. Followed by 4" long fruits. Zone 10 or indoors.

Sedum dasypyllum -- Corsican Stonecrop -- Evergreen perennial groundcover forms a low carpet of tiny round powdery blue-grey leaves, remaining evergreen in mild regions. Clusters of white star flowers appear in early summer. Zones 5-9.

Sedum 'Purple Emperor' -- Large, deep red-black foliage is attractive early in the year, and is followed by abundant branching heads of dusky rose flowers that fade to bronze as they age, the dead flowers looking good even in winter. The flowers attract butterflies, and are good for cutting. If soil is too rich, this plant may become lanky; this is fixed by pinching back. Zones 3- 9, sun.

Sedum oxypetalum -- Tree Sedum -- Click on the link for a more interesting picture. This plant is surprisingly hard to find and hardier than most think. Burl Mostel at Rare Plant Research says it has survived 15°F in dry conditions. We wouldn't let it freeze, though, in case Burl is incredibly lucky; the plant is from Mexico, after all. It does make a find bonsai specimen, though of course not really a tree, just treelike in form. Growing to 4' tall, a crowning touch is its bright red starlike flowers with white sepals.

Sedum spurium -- 'Bronze Carpet' -- Mat of bronzy foliage with bright rose-pink flowers in July and August; rock garden, ground cover, or roof garden selection. Requires excellent drainage. Zone 3.

Sedum spurium -- 'Voodoo' -- The darkest of the spuriums, it grows like Sedum 'Dragon's Blood', but lower and deep mahogany red. Rock garden, ground cover, or roof garden selection. Requires excellent drainage. Zone 3.

Sisyrinchium macrocarpum -- A species from Argentina , but reportedly hardy to at least zone 7. Largish for the genus, to 8-10", with large flowers as well. The bright yellow flowers have a chocolate ring at the base of the petals. Flowering period is long, late spring through fall, and the species doesn't reseed as readily as many. Miniature iris-like leaves are slightly bluegreen.

Stapelia gigantea -- This looks much like a miniature Cereus cactus, with a fat, upright, ribbed stem, but without spines, like all Old World cactus analogs. Though it grows to less than a foot tall, it produces a starfish-shaped flower that can be a foot across. Hardy outside only in the warmest climates, it grows easily in a sunny or partly-sunny window. It's really best to grow it in a greenhouse, though, if you can't grow it outside, or move it out when in bloom. That's because an alternative common name is 'Carrion Flower' and it is pollinated by flies. 'Nuff said, but I've noticed that this rather important fact is curiously omitted by some other growers. Native to South Africa.

Stauntonia hexaphylla -- Little-known twining climber with compound leaves and creamy white, purple-tinged fragrant flowers, followed by edible sausage-like fruits. Related to the Chocolate Vine, Akebia. Japan. Zones 7-10.

Stipa robusta -- Sleepy Grass -- A dryland grass from plains and hills from South Dakota west to Montana and south to Texas and New Mexico. It consists of low mounds of shiny grasslike leaves from which protrude upright stems topped with feathery seed heads. In the wild, seeds can be infected with a fungus that contains the hallucinogen LSA, causing drowsiness in grazing animals, hence the common name. Grows to around 4'. Zone 8.