Most people picture melastomes as flowering shrubs, but the family also contains small, creeping forest-floor herbs grown for their foliage. Bertolonia is the best known of these, a small genus from the Atlantic Forest of Brazil.
Quick facts. Family: Melastomataceae. Range: the Atlantic Forest of eastern Brazil. Habitat: humid, shaded forest floor and mossy rocks. Growth form: low herbs. Main interest: patterned leaves, often with a metallic sheen. Typical use: terrariums and humid greenhouses.
An unusual melastome
Bertolonia is a small genus, and its plants are very different from the tall shrubs of other genera. They stay low, usually only a few centimetres to a little over a hand's height, and spread across the humid forest floor and over damp rocks and mossy banks. The leaves are the main attraction: depending on the species and variety, they may be dark green with silver or pink veins, mottled, marbled or spotted, sometimes with an iridescent shimmer in low light.
This patterning is not fully explained. Variegated foliage on forest-floor plants is thought to relate to life in deep shade, where surface texture and pigment layers may influence how light is captured and reflected, though the details vary by plant group.
Living conditions in the wild
The Atlantic Forest, running along Brazil's coast and inland slopes, is one of the world's most biodiverse and most reduced forest biomes. Bertolonia grows where air humidity stays high, temperatures are mild and direct sun rarely reaches the ground. These plants are not built for dry air or strong light.
Flowers
The flowers are small, usually pink or white, held above the leaves on short stalks. They reward a close look: like their larger relatives, they have petals arranged around curved stamens with pore-opening anthers. In cultivation, though, the foliage is the reason to grow them.
Growing Bertolonia
Bertolonia has a reputation for being fussy, and that reputation is fair if you treat it as an ordinary houseplant. It does best in conditions closer to a rainforest floor.
- Humidity: consistently high. A closed or semi-closed terrarium, or a humid cabinet, is far easier than an open shelf.
- Light: bright shade or low-intensity artificial light. Direct sun scorches the leaves quickly.
- Temperature: mild and steady, avoiding both chills and heat spikes.
- Substrate: loose, airy, moisture-retentive and slightly acidic, such as a blend of sphagnum, fine bark and perlite.
- Water: low-mineral water such as rainwater is kinder than hard tap water.
For details on setting up this kind of environment, see growing melastomes in terrariums and watering and humidity.
Why it is worth knowing
Bertolonia is a reminder that the family is far more varied than its flowering shrubs suggest. It also shows how many species depend on narrow, shaded, humid habitats that can disappear with a small change in land use. Buy only nursery-propagated plants, never wild-collected ones.