Begonia masoniana ‘Iron Cross’

A limestone-region species from China and Vietnam

Begonia masoniana ‘Iron Cross’ is a horticultural selection of Begonia masoniana, a rhizomatous species native to Guangxi in southern China and to northern Vietnam.

Wild Begonia masoniana occurs in sheltered forest and limestone country. Its habitat combines warm, humid air, seasonal rainfall and light filtered through surrounding vegetation.

Care for rooted rhizomes and foliage

Root care and propagation

Begonia masoniana ‘Iron Cross’ grows from a thick surface rhizome and should not be staked by its hairy petioles. Point the rhizome across a broad pot and divide only a rooted growing end.

Watering

Begonia masoniana ‘Iron Cross’ is ready for water after the upper layer of the substrate has dried while the shallow root zone below remains faintly moist. Test beneath the active end of the rhizome on the plant.

Light

Give Begonia masoniana ‘Iron Cross’ a position close to an east or north-east window, or close to a south or west window behind a light curtain. The light is too strong if it heats the leaves and the upper leaf surface bleaches or scars and the rhizome dries unevenly.

Substrate and roots

The root structure of Begonia masoniana ‘Iron Cross’ is a surface-running rhizome with fine, shallow feeder roots. Choose a broad container only slightly larger than the roots, leaving the rhizome visible across the surface.

Temperature

A cold sill can chill the shallow roots before the room thermometer shows a problem.

Repotting

Give Begonia masoniana ‘Iron Cross’ a new pot when the rhizome reaches the rim, roots fill the shallow pot, water moves unevenly or the substrate has compacted. Set the plant so the growing rhizome has room to advance across the fresh mix.

When Begonia masoniana ‘Iron Cross’ needs attention

Dark cross appears to spread

The chocolate marking naturally darkens along the veins as a leaf matures. Firm dark tissue that follows the cross pattern is normal pigment. Isolate the plant and remove any translucent area, yellow halo or soft patch that continues to spread beyond the cross.

Puckered leaves droop or curl

A partly dry root ball may cause temporary drooping. A longer dry spell leaves the hairy edges crisp. If the mix is still wet, inspect the roots and allow more air around them. Restore even moisture only after distinguishing thirst from root loss.

Water remains in the coarse leaf surface

The raised texture and hairs can hold droplets. Blot accidental water, improve gentle airflow and water at the mix. Remove a leaf when grey fuzzy growth develops on soft tissue or when a water-soaked area keeps expanding beyond its yellow boundary.

Rhizome becomes soft or buried

A healthy rhizome should remain firm at the surface. Lift it from dense wet mix, cut away every soft dark section and reroot a firm end piece shallowly. If most of the rhizome is affected, save an unspotted healthy leaf for propagation before the crown collapses.

White powder appears on the hairy leaves

Powdery mildew can spread across both sides of the coarse blade. It returns after wiping, unlike dust or mineral residue. Remove heavily affected leaves, increase air exchange and keep foliage dry. Apply a product labelled for mildew on ornamentals if needed, testing first on one leaf.

Begonia masoniana ‘Iron Cross’ is toxic to people and pets

• Keep this plant away from children, cats and dogs.
• The roots and rhizomes contain the highest levels of soluble oxalates, and the sap can irritate skin.
• Chewing may cause mouth irritation, drooling, vomiting or stomach pain. Contact a veterinarian or medical professional if symptoms develop.

How did Begonia masoniana get its name?

Begonia honours Michel Bégon. The epithet masoniana honours the British plantsman Maurice Mason.

Carl Linnaeus established the genus Begonia in 1753 in Species Plantarum, page 1056.

Rudolf Christian Ziesenhenne first described Begonia masoniana in 1971 in Begonian, volume 38, page 52; Edgar Irmscher had proposed the name.