Coleus

Farfugium japonicum is an evergreen rhizomatous perennial native to streamsides and rocky seashores of Japan, Korea, Taiwan, and coastal China, where it is known as tsuwabuki (石蘗). In gardens it delivers bold, kidney-shaped leaves up to 10 inches across and cheerful yellow daisy flowers in autumn and winter - a genuinely useful combination for dark, damp corners. The honest catch is toxicity: the plant contains petasitenine, a carcinogenic pyrrolizidine alkaloid; it must be kept out of reach of children and pets and handled with care, and it is frost-tender above USDA zone 7b, dying back or suffering severe leaf scorch in hard freezes.

Hakonechloa macra is a slow-growing, clump-forming deciduous grass endemic to Japan, naturally found on rocky woodland slopes near Mount Hakone and across Honshu. It is prized in shaded gardens for its gracefully cascading, fountain-like mounds of thin, arching leaves and warm autumn tones of red and pink. The honest catch is pace and site sensitivity: it is among the slowest ornamental grasses to establish, struggles badly in hot dry summers without consistent moisture, and is prone to leaf scorch if sited in too much sun - it needs rich, reliably moist soil to earn its reputation.

Persian buttercup is a tuberous herbaceous perennial native to the eastern Mediterranean - from Cyprus, Crete, and Turkey across to Iran, Iraq, and the Levant - where it blooms in rocky scrub and meadows in late winter through spring. In gardens it is prized for its luminous, poppy-like flowers in red, orange, pink, yellow, and white (wild single forms) or the dense, multi-layered doubles of commercial 'Tecolote' and 'Bloomingdale' strains beloved by florists. The honest catch is its frost-tenderness: the tubers are killed below roughly 14°F, so gardeners in USDA zones 7 and colder must lift and store them after foliage dies down each summer, and the whole plant contains protoanemonin, a skin and gut irritant toxic to humans and livestock on contact or ingestion.

String of buttons is a rambling South African succulent (Crassulaceae) native to rocky slopes and thicket vegetation in the Cape Provinces and KwaZulu-Natal, where it scrambles through shrubs on long, unbranched stems. In frost-free gardens (USDA zones 9b–11b) it is a textural ground cover, rockery plant, or spiller in containers; everywhere colder it is a houseplant or frost-protected patio succulent. The honest catch is twofold: it is frost-tender and will be killed or disfigured by a hard freeze, and - like its toxic genus-mates such as the jade plant - it is best treated as toxic to cats and dogs, so it is not a safe choice for pet-accessible plantings.

Gentiana acaulis is a low, mat-forming alpine perennial native to the mountains of central and southern Europe - the Alps, Pyrenees, and Balkans - where it grows in short turf and rocky meadows from 2,625 to 9,843 feet elevation. In gardens it is prized for its astonishing, deep-blue trumpet flowers in late spring, and it has received the RHS Award of Garden Merit. The honest catch is its notorious habit of "sulking": well-established plants can refuse to flower for years with no apparent cause, and the gardener's only remedy is to dig and replant the mat a few inches away - a maddening behaviour that makes it a reliable showpiece in some gardens and a frustrating non-bloomer in others.

A bold, clump-forming evergreen perennial from South Africa, grown for big rounded umbels of trumpet-shaped blue (or white) flowers held on tall bare stalks above arching, strap-shaped leaves in mid-to-late summer. It is widely sold as "lily of the Nile," but that is a misnomer - the plant is South African (the Cape provinces and KwaZulu-Natal), not from the Nile. Spectacular and easy in warm climates, this evergreen Agapanthus is frost-tender, so in cold-winter areas it is grown in a container and overwintered under cover. The RHS has given several Agapanthus praecox forms its Award of Garden Merit and rates this evergreen species half-hardy (H3 - needs winter protection).