Begonia maculata Raddi
Polka dot begonia · Angel wing begonia · Spotted begonia
- Family
- Begoniaceae
- Native to
- South-east Brazil
- Habit
- Cane-type perennial
Where it comes from
One state. Kew’s distribution field says “Brazil Southeast”, but Kew’s own summary sentence on the same taxon is finer — “the native range of this species is Brazil (Rio de Janeiro)” — and the Brazilian national flora agrees exactly: endemicendemicFound naturally in one place and nowhere else.Glossary, Rio de Janeiro only, Atlantic Forest.12 The habitat is rainforest and rocky outcrops.2
It is terrestrial, not an epiphyteepiphyteA plant that grows on another plant, taking nothing from it — perched in bark and leaf litter rather than rooted in soil. It is why so many houseplants want an airy mix rather than compost.Glossary. No tier-1 or tier-2 source calls it one; the national flora codes the substrate Terrícola, and the RHSRHSThe Royal Horticultural Society. Its plant register and its Award of Garden Merit are among the few horticultural authorities worth citing.Glossary describes a fibrous-rooted cane-stem begonia.23 So it goes in ordinary potting compost, not a bark mix.
Two traps on Kew’s own page worth naming, since they are the first thing a careful reader will hit. Its morphology block calls the plant “climbing” — that block is credited to a Colombian dataset describing cultivated Colombian material and is wrong for the wild plant. The same tab’s elevation range of 1,580-1,700 m and its Andean region come from the same place. Neither describes Rio de Janeiro.4
Mature height is about 0.5-1 m, or two to three feet, in two to five years.35
Naming and description
Giuseppe Raddi published the name in 1820.6 The type was collected on Morro do Corcovado — the Rio hill that Christ the Redeemer has stood on since 1931 — and the holotype is in Florence.7
Is the plant everyone grows ‘Wightii’? Yes, and it is still B. maculata. The name was published as a botanical variety, B. maculata var. wightii Fotsch (1933); Kew sinks it into the species, and the Bishop Museum records the same synonymy.89 The decisive source is a 2005 nomenclatural paper which lists Fotsch’s varieties with no type indicated, records that no herbarium material matching them was found in Berlin, Geneva, Kew or Paris, and concludes they should be treated as probable cultivarscultivarA plant selected and propagated by people rather than described from the wild. Written in single quotes after the species — Monstera deliciosa 'Thai Constellation' — and never italicised.Glossary.7 The RHSRHSThe Royal Horticultural Society. Its plant register and its Award of Garden Merit are among the few horticultural authorities worth citing.Glossary carries ‘Wightii’ as a cultivarcultivarA plant selected and propagated by people rather than described from the wild. Written in single quotes after the species — Monstera deliciosa 'Thai Constellation' — and never italicised.Glossary of the species, with no award.10 So: the species, of which the widely grown clonecloneEvery plant propagated by cutting or division from one original, and so genetically identical to it. Most named cultivars are a single clone.Glossary is a named selection. I searched three ways for the claim that trade plants are hybrids and found nothing supporting it at any level of source.
Silver spots on olive green, red beneath, on asymmetric wing-shaped leaves held on bamboo-like canes.
Fun facts
- The spots are air, not pigment — and they are nearly free. In begonias this kind of pale patterning comes from air spaces under the epidermis that scatter light. The surprise is the cost: one study measured maximum quantum yield and Fv/Fm in pale and green zones of the same begonia leaf and found no significant difference, unlike the genuinely pigment-deficient variegationvariegationPatches of leaf with little or no chlorophyll, so they read as white, cream or yellow. The pale tissue cannot feed itself, which is why a variegated plant grows more slowly than a plain one.Glossary it compared against.11 So do not give this plant extra light on the theory that spots cost it chlorophyll.
- They are also not the famous iridescent begonia chloroplastschloroplastThe compartment inside a plant cell that does photosynthesis. White leaf tissue has none that work, which is why it cannot pay its own way.Glossary. The photonic-crystal work everybody cites was done on the blue-iridescent B. pavonina, and a survey of forty begonia taxa found the specialised plastids in only some, with a much lower photosynthetic efficiency than ordinary chloroplastschloroplastThe compartment inside a plant cell that does photosynthesis. White leaf tissue has none that work, which is why it cannot pay its own way.Glossary.1213 B. maculata is in neither study. Two entirely different mechanisms get conflated constantly.
- The red underside does not bounce light back into the leaf. This is the explanation every care blog gives, and it was tested — on a naturally variegatedvariegationPatches of leaf with little or no chlorophyll, so they read as white, cream or yellow. The pale tissue cannot feed itself, which is why a variegated plant grows more slowly than a plain one.Glossary begonia with red and green patches on the same leaf, an unusually clean control — and rejected: no greater red reflectance, similar fluorescence, and gas exchange not significantly different at P = 0.73.14 The authors propose photoprotection by attenuating green light instead.
- Do not try to root it from a leaf. That trick belongs to rhizomatous, rex and tuberous begonias. Cane types like this one go from stem cuttings — and one cane cut into nodenodeThe point on a stem where a leaf attaches and new roots and shoots can form. A cutting without one is a leaf on a stick: it cannot grow.Glossary sections can give a dozen.155
- Misting will not stop the powdery mildew, and may be why it is there. Begonia powdery mildew does not need free water on the leaf to infect;16 what it wants is 70-85 °F (21-29 °C), low light, and humid nights following drier days — an indoor windowsill, in other words.1718 Above 85 °F (29 °C) it is inhibited.18
Care
- Light
- Bright indirect, no direct midday sun. UF/IFAS's 1,500-2,200 foot-candles for rex begonias is a Florida production figure under shade, not a windowsill target — Clemson classes anything over 1,000 as very high and notes few homes reach it. The useful indoor floor is 150-300 foot-candles, which kept trial plants in good condition for nine weeks where 75 did not.
- Water
- Water through once the top third of the mix has dried, and err dry — these rot from below far more easily than they wilt. Keep water off the leaves and out of the crown: that is a disease instruction, not a cosmetic one, and five separate extension services give it.
- Humidity
- Above 50% for a rex. Cane types are not fussy and do not need a humidifier. But humidity without air movement is the trap here — three different pathogens want exactly the conditions that raising humidity creates, so ventilation and clearing dead leaves matter more than the number.
- Temperature
- 65-80 °F (18-27 °C), floor 55 °F (13 °C). A rex prefers 72-80 °F (22-27 °C) by day and 60-65 °F (16-18 °C) at night — the cool-night preference of a montane plant — while cane types are content a little cooler.
- Substrate
- A light, free-draining, peat- or coir-based mix at pH 5.7-6.4, in a shallow pot. The shallow pot is the same physics as the watering advice: less wet mix sitting under a shallow root system.
- Fertilizer
- Dilute and frequent beats strong and occasional — a balanced feed at 100-150 ppm nitrogen monthly, or quarter strength every fortnight. Feed cane types higher in potassium and rhizomatous types higher in nitrogen. Never feed a resting plant.
- Propagation
- Leaf cuttings for a rex — triangular wedges each containing a main vein, set about 1 cm into the mix under a dome, roots in three to five weeks with a shoot shortly after. Cane types do not root from a leaf: take stem cuttings of 8-10 cm with two or three nodes. Rooting hormone speeds it up but is not necessary.
- Dormancy
- Depends on the type, and getting this wrong kills plants. Cane-stemmed begonias are evergreen and simply slow down. Rex begonias often do rest — they stop, and may drop every leaf — and the trigger is photoperiod: UF/IFAS records that they need a 14-hour day to keep growing, so a timer prevents it. A resting rhizome wants barely moist mix and no feed at all until spring.
- Common problems
-
- Powdery mildew is the defining disease. It does not need water on the leaf to infect, and it is favoured by 60-80 °F (16-27 °C), shade and humid nights after dry days — which describes an indoor windowsill exactly. Above 85 °F (29 °C) it stops
- Botrytis wants humidity above 85% and a film of moisture lasting eight to twelve hours, and it turns into crown rot on an established plant or base rot on a cutting
- Bacterial leaf spot (Xanthomonas campestris pv. begoniae) splashes from leaf to leaf, has no cure, and survives a year in a dried fallen leaf — so clearing dead foliage off the mix is disease control, not tidiness
- A bald rex in midwinter is usually resting, not dying. Firm rhizome and no leaves in January is dormancy; a soft, blackened, water-soaked stem base is Pythium, and the two call for opposite responses
- Misting is bad advice for this genus, and the RHS and Clemson both say so outright — spray the air around the plant instead, or raise humidity by other means
- Every part carries soluble calcium oxalates and the ASPCA says the most toxic part is underground. That matters more for a rex than most: the rhizome sits on the surface of a shallow pot, within reach