Rieger begonia

Hippeastrum x hybridum is a complex garden hybrid derived from six or more wild Hippeastrum species native to tropical and subtropical South America, developed through intensive breeding since the late 18th century and now the dominant "amaryllis" sold worldwide as a holiday bulb. It produces spectacular trumpet-shaped flowers - 5 to 8 inches across - on stout leafless scapes in red, pink, white, orange, salmon, or bicolour, making it one of the most dramatic winter-flowering houseplants available. The honest catch is toxicity: the entire plant, especially the bulb, contains lycorine and related alkaloids at concentrations that cause vomiting, salivation, tremors, and hypotension in pets and children, so it must be placed out of reach and handled with care.

A tropical aroid from the warm, humid rainforests of Colombia and Ecuador, where it grows as an epiphyte, and one of the best-known flowering houseplants. Also called flamingo flower, it carries glossy, heart-shaped leaves and long-lasting, waxy spathes, most often bright red but also pink, orange, white or green, each around a short upright spadix. NC State Extension says each bloom lasts up to four weeks and the plant flowers several times a year, and the Missouri Botanical Garden says it can flower year round in the right conditions. That takes bright, indirect light, steady warmth and high humidity, and outside USDA zone 11 and warmer it lives indoors. NC State Extension, the RHS and Wikipedia all warn that every part contains calcium oxalate, harmful to people and pets if chewed and irritating to skin and eyes.

A compact evergreen perennial of the nettle family (Urticaceae), grown worldwide as a houseplant for its round, glossy leaves, each held flat on a long stalk attached near its centre. The Flora of China records it on shaded, moist rocks in mountain forests of southwestern Sichuan and western Yunnan and calls it very rare and possibly endangered in the wild, though widely grown as a pot plant. NC State Extension calls it easy to grow in bright, indirect light, and the RHS recommends it as a houseplant; outside USDA zones 9 and warmer it lives indoors. No poison-control source covers this species, so its safety around pets is not established.

The true Christmas cactus - the hybrid Schlumbergera x buckleyi - a long-lived epiphytic holiday cactus grown indoors almost everywhere for its arching, segmented stems and its rose-to-magenta flowers that open in mid-winter, around Christmas. It is worth getting the identity right, because most plants sold and labeled as 'Christmas cactus' are actually the Thanksgiving cactus, Schlumbergera truncata. You can tell the two apart by the edges of the flat stem segments and by when they bloom: the true Christmas cactus has rounded, scalloped segment margins and flowers a few weeks later, in mid-winter, while the Thanksgiving cactus has sharp, claw-like teeth and blooms from late fall into early winter. Unlike a desert cactus, this is a forest epiphyte that grows on tree branches in the Atlantic coastal forest of southeastern Brazil, so it wants bright indirect light, a free-draining mix, sparing water, and - to set its buds - cool nights and short days. A reassuring point that sets it apart from many houseplants: it is non-toxic to cats and dogs. One more field mark clinches it: the true Christmas cactus has rose-pink pollen and flowers that hang almost regularly (radially), where the Thanksgiving cactus has yellow pollen and asymmetric blooms held out nearly horizontally.

A spring-flowering bulb grown for dense upright spikes of waxy, star-shaped florets in blue, purple, pink, red, or white - famous for an intense, sometimes overpowering fragrance. Plant bulbs in mid-fall for an April bloom; flower quality typically declines after the first year, so the densest spikes often need replanting every couple of seasons. Every part of the bulb is mildly toxic and the sap can cause contact dermatitis, so gloves are advised when planting.

Cushion haworthia is a tiny, choice, clump-forming succulent whose plump, soft, blue-green leaves end in translucent "windows" - in the wild the plant pulls itself down into the soil and lets light reach its inner tissues through these clear leaf tips, an adaptation to the bright, dry Karoo light. POWO (Kew) places it native to the Eastern Cape of South Africa (Cape Provinces). It is a jewel for a pot or a windowsill rather than a garden plant. Unusually for this group of succulents, it prefers BRIGHT INDIRECT light or part shade rather than harsh full sun, which scorches and reddens it; give it sharp drainage and water sparingly during growth, far less in winter. OVERWATERING - and cold, wet soil - is the main way it dies, and it is FROST-TENDER (RHS rates it tender, H1c-H2), so almost everywhere it is grown as a houseplant or in a frost-free greenhouse. It is grown for its jewel-like translucent foliage, not as a food plant, and it rarely flowers in cultivation.