Scientific Name (Genus/Species): Scutellaria altissima

Family: (Lamiaceae)

(P) to 3′. Soaring Skullcap. Southeast Europe, Caucasus. Bushy perennial with light green, serrated, slightly downy, oval leaves. Numerous, one-sided racemes of many, pale blue, tubular, lipped flowers. A welcome presence in our Gravel Garden. Well-drained soil. Sun/partial shade. 3 & T2

Scientific Name (Genus/Species): Sedum fosterianum subsp. elegans

Family: Crassulaceae

(P) to 8″. Stonecrop. NW and SW Europe. Lovely hardy sedum with blue-green, needle-like foliage. Prolific midsummer bloomer with attractive corymbs of star-shaped, yellow flowers and persisting attractive flat seedheads. Perfect for the sunny rock garden.  4 & T1

Scientific Name (Genus/Species): Sedum kamtschaticum

Family: (Crassulaceae)

(P) to 8″.  Japan to Kamchatka.  Spreading clumps of fleshy, obovate, bright green foliage with irregularly scalloped margins create a thick mat for sunny areas.  Unbranched flower stalks produce flattened cymes of deep yellow, starry flowers appearing as a veritable carpet of gold.  Beautiful when creeping along the edge of a pathway or spilling out of a crevice.  Mid to late summer.  Accommodating and tough.  Well-drained soil.  Sun.  4 & T1

Scientific Name (Genus/Species): Sedum middendorffianum

Family: (Crassulaceae)

(P) to 8″.  Chinese Mountain Stonecrop.  East Siberia to North China.  A non-stop performer in all seasons.  Narrow, spathulate, leathery, deep green leaves with toothed tips whorl around showy red stems.  In early summer, the dense, semi-evergreen mats support multitudes of five-petalled, bright flowers ranging in colour from yellow to fiery orange-red.  Seedheads dry to a beautiful deep maroon, persisting for the remainder of the season, atop the spectacular autumn foliage show in brilliant shades of red.  One of our favourite, most reliable plants for the well-drained, full-sun garden.  4 & T1

Scientific Name (Genus/Species): Semiaquilegia ecalcarata

Family: (Ranunculaceae)

(P) to 16″.  False Columbine.  A native of eastern Asia with exquisite mauve-purple, bell-shaped, nodding flowers resembling spurless Columbines.  A delicate addition to the woodland.  We have ours self-sowing nicely around the troughs near the Gardeners’ Bothy.  Blooms in late spring.  Sun/partial shade.   4 & T2

Scientific Name (Genus/Species): Senna marilandica (syn. Cassia marilandica)

Family: (Caesalpiniaceae)

(P) to 6′.  Southern Wild Senna.  Eastern North America.  Very similar to the above, the flowers of Senna marilandica have styles with short appressed hairs, while the flowers of Senna hebecarpa have styles with long spreading hairs.  Southern Wild Senna, because its range doesn’t extend as far north as a closely related species, Senna hebecarpa (Wild Senna). Blooms from July to September.  Well-drained soil.  Sun/partial shade.  1 & 3 & T3

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Scientific Name (Genus/Species): Sibiraea laevigata

Family: (Rosaceae)

Hardy shrub to 7′.  China.  Grown for its beautiful sea green foliage and deep red-brown shoots.  Dense, terminal panicles of small, five-petalled, white flowers with numerous stamens in late spring and early summer.  The older bark is furrowed and interesting.  Sun.  3 & T2 & Δ

Scientific Name (Genus/Species): Silene armeria

Family: (Caryophyllaceae)

(A) to 8″.  Sweet William Catchfly.  Europe.  Grey-green, glaucous leaves and loose clusters of tubular, bright rose-pink flowers with five notched petals.  Flowers profusely July through August.  A cheerful and easy self-sower.  An old fashioned beauty that is a mainstay in grandmother’s garden.  Sun.  3 & T2

Scientific Name (Genus/Species): Silene virginica

Family: (Caryophyllaceae)

(P) to 18″.  Fire Pink.  Eastern North America.  A lovely wildflower that features brilliant, two-inch, scarlet red flowers, each with five spreading, notched-at-the-tip petals plus sepals which are united into a long sticky tube. Flowers bloom in spring atop slender, downy, and sticky stems clad with narrow, lance-shaped, green leaves. Ruby-throated hummingbirds are the principal pollinator of Silene virginica.  Flowers also provide nectar for native bees, butterflies, and nocturnal moths. Well-drained soil.  Part sun to part shade. 3 & T2

Scientific Name (Genus/Species): Silphium terebinthinaceum

Family: (Asteraceae)

(P) to 6′. The Prairie Dock. Tall stems of yellow daisies. The giant leaves can reach three feet in length. Rough, flat, dark green and extremely handsome leaves. Fabulous foliage plant. Sun. 3 & T2

Scientific Name (Genus/Species): Sinacalia tangutica (syn. Ligularia tangutica)

Family: (Asteraceae)

(P) to 3′. China. Leave your gardening friends guessing with this unusual and striking plant. Terminal compound clusters of small, lemon yellow daisies contrast beautifully with the bright green, sharply pinnate, incised foliage. Definitely a talking point. Blooms well into September. Moist soil. Sun/partial shade. 4 & T2

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Scientific Name (Genus/Species): Sinningia sellovii

Family: (Gesneriaceae)

(TP) to 2′.  Brazil. Long terminal panicles of pendant, swollen tubular flowers from bright red to dark salmon-pink.  Several long, arching upright stems arise from a woody, tuberous base.  Pairs of soft textured elliptical, minutely toothed leaves occur along the stems.  An unusual Gloxinia that would make an attractive houseplant for a sunny window.  Blooms late summer to fall.  Sun.  4 & T1

Scientific Name (Genus/Species): Sisymbrium luteum (syn. Hesperis lutea)

Family: (Brassicaceae)

(P) to 4′. Japan and Korea. Forms a bushy clump of coarsely pilose, pinnate, grey-green foliage that freely produces dense, elongated racemes of four-petalled, pale yellow flowers in summer. Good for cutting. Well-drained soil. Sun/partial shade. 4 & T3

Scientific Name (Genus/Species): Sisyrinchium angustifolium

Family: (Iridaceae)

(P) to 12″. Narrow-leaved Blue-eyed Grass. Eastern North America. Delicate fans of narrow, grass-like foliage produce an always welcome display. The star-shaped blooms of six pale violet-blue tepals each tipped with a small point and sporting a yellow central eye accentuated by the yellow stamens and stigma. Blooms late spring and early summer. A cheery, easy going and charming native for the rock garden, woodland edge or the meadow. Sun. 3 & 7 for 90 days then T2

Scientific Name (Genus/Species): Sium sisarum

Family: (Apiaceae)

(P) to 3′. Skirret, Ratbait. Europe to East Asia. Aromatic, shiny leaves with three to eleven leaflets that are lanceolate and toothed. Umbels of small, white flowers with involucral bracts. Long-blooming. Moist soil. Sun. 3 & 6