BEGONIA REX: CHARACTERISTICS, HABITAT, VARIETIES, REPRODUCTION, CARE - BIOLOGY - 2025

Begonia rex is a herbaceous species cultivated as an ornamental plant that belongs to the Begoniaceae family. Known as Painted Leaf Begonia, Royal Begonia, King Begonia, or Thousand Colors Plant, it is a plant native to Northeast India.

It is characterized by a thick underground rhizome, as well as ovate, sinuous leaves of metallic green color with a central silver stripe and purplish edges. Although it produces small flowers, its commercial interest is limited to its attractive leaves that stand out for the variety of shapes and colors.

Begonia rex. Source: pixabay.com

Begonias are considered indoor plants, as they do not tolerate cold. In addition, they require sufficient solar radiation to display their vivid colors, yet they do not tolerate the direct rays of the sun.

It grows on fertile substrates of acid pH and well drained, preferably a mixture of black soil, peat, sand and organic matter. As it is a potted crop, it is convenient to transplant to a larger pot when the substrate has excessive rhizome growth.

Leaf begonias are one of the main indoor ornamental plants, distributed in tropical and subtropical areas around the world. In gardening they are used to form beds or borders and cultivated as indoor plants in pots or hanging containers.

General characteristics

Begonia rex is a herbaceous plant with attractive evergreen leaves that can reach 30-40 cm in height. It is characterized by its robust, underground and superficial rhizome, which generates abundant adventitious roots, measures 8-15 mm in diameter and functions as a reserve organ.

Begonia rex's main attraction is its large rosette-shaped leaves, succulent texture, and rough appearance. Depending on the variety, the leaflets can be conch-shaped or spherical, with wavy or serrated margins and a great diversity of tones.

Indeed, the leaves present different patterns and shades that vary from green, yellow, cream, white, silver, red, pink, purple or black. They are usually glabrous on the upper surface, slightly tomentose on the underside, and are arranged on a long hairy petiole.

The small staminate pinkish flowers are grouped in inflorescences 10-15 cm high. The fruit is a trilocular capsule with small crescent-shaped lateral wings.

Begonia rex leaf. Source: Meise Botanic Garden

Taxonomy

- Kingdom: Plantae

- Division: Magnoliophyta

- Class: Magnoliopsida

- Order: Cucurbitales

- Family: Begoniaceae

- Genus: Begonia

- Section: Begonia sect. Platycentrum

- Species: Begonia rex Putz.

Etymology

- Begonia: the name of the genus was given in honor of the French sailor, naturalist and botanist Michel Bégon, governor of Santo Domingo in the seventeenth century.

- rex: the specific adjective in Latin that means "king."

Synonymy

- Platycentrum rex (Putz.) Seem.

Hybrids

- Begonia × clementinae Bruant

- Begonia × conspiqua Sander

- B. × gemmata Sander

- B. × inimitabilis De Smet

- Begonia × leopardinus Van Houtte

- Begonia × margaritacea HJVeitch

- B. × punctatissima Sander

- B. × splendidissima De Smet.

Petioles and flowers of Begonia rex. Source: Meise Botanic Garden

Habitat and distribution

The Begonia rex species is native to the tropical and subtropical regions of Asia, Africa, Central and South America. In the wild it is found in understory and mountain slopes at an altitude of 400-1,100 meters above sea level in certain regions of India, China and Vietnam.

The current varieties of Begonia rex are hybrids that have been developed as ornamental plants for indoor use. Its evolution from wild plants in the understory has allowed its adaptation to shading conditions to flourish.

Varieties

Begonia rex 'Escargot'. Source: Montrealais

- 'Merry Christmas': leaves with green edges dotted with white, the center pink with hues of garnet tones.

- 'Fireworks': leaves with dark brown veins on a silver background and margins of purple tones.

- 'Escargot': the leaves have an endless spiral shape with bands between green and gray.

- 'Curly Fireflush': green or silver spiral leaves with abundant reddish hair on the veins, on the upper side and on the underside.

- 'Miami Storm': large rounded leaves of bright red tone and curly margins of black color, as well as around the veins.

- 'Red Robin': similar to the 'Miami Storm', but the leaves are smaller and oval.

Reproduction

Flowers of the Begonia rex hybrid 'Merry Christmas'. Source: Meise Botanic Garden

Begonia can reproduce in different ways, by leaf cuttings, by division of leaves or rhizomes, seeds and in vitro cultivation.

Propagation by cuttings

Propagation by cuttings is a practical form of vegetative propagation, however it is not very profitable. The petioles, with or without leaves, are placed directly on rooting trays or pots with a fertile substrate.

A variation of the technique is to place the cuttings in a container of fresh water and once the rooting has started they can be transplanted into pots. In both cases it is a slow and cumbersome process, since it requires a lot of manipulation that favors the transmission of viruses and phytopathogenic fungi.

Division of leaves and rhizomes

This technique requires healthy and vigorous leaves that have reached full development, as well as robust rhizomes in full growth. The leaves are cut into triangular pieces trying to maintain 1-2 veins for each piece, the rhizomes are divided keeping 2-3 buds per cut.

The leaf cuts are placed in rooting trays maintaining a constant temperature of 18-20 ºC and 70% relative humidity. It is necessary to maintain greenhouse conditions, protected from direct sunlight and applying frequent nebulisations to avoid dehydration of the tissues.

The rhizome pieces should remain for 2-3 days in cool environments for the wounds to heal before placing in rooting trays. Subsequently, they are placed under a plastic tunnel with a temperature of 18-20 ºC, 80% relative humidity and constant nebulization.

It is advisable to use some type of plant phytohormone that favors the development of adventitious roots. At 45-60 days the first roots emerge, being the precise moment to transplant into pots with a humid and fertile substrate.

Seeds

Propagation by seeds is a slow process that is used only in research work to obtain hybrids or new varieties. Furthermore, the seeds are often not very fertile, difficult to handle and produce very heterogeneous plant material.

Culture

The in vitro culture technique is a viable alternative to obtain a large quantity of genetically homogeneous plants at low cost and high quality. In the case of Begonia rex, it is recommended to obtain the explants from the rhizomes, since the leaves present "chimeras" that do not reproduce similar clones.

Care

Variety of shapes and colors of Begonia rex. Source: Mokkie

Location

Begonia rex is an ornamental indoor and outdoor plant. Grown in pots or indoor planters, it should be located in a cool environment with partial shade, but with good lighting throughout the day.

Light has a significant influence on the chromaticism of its foliage, so when planted outdoors it must receive sunlight, although protected from direct rays. In cold climates, it has the ability to adapt to solar radiation and produce more intensely colored leaves.

Floor

As an ornamental plant grown in pots, it requires a loose and porous substrate, with a high content of organic matter and well draining. A mixture of black soil, sand, peat, and compost that maintains a pH around 4.5-5.5 is ideal for vigorous, glossy leaf begonias.

illumination

The best location in a room is a window facing north. In this way, it will get enough light during the day to thrive and it will not receive direct sun that can burn its leaves.

Temperature

The ideal temperature for its development is between 18-20 ºC. During the summer it is advisable to place it in an airy place out of reach of direct solar rays.

It is a plant susceptible to low temperatures, where from values ​​lower than 12 ºC they tend to dry and wilt the leaves. On the other hand, environments with wide temperature ranges between day and night favor the production of larger leaves and bright colors.

Irrigation

Begonia rex leaves have a succulent texture, so they need to keep the substrate moist all the time. When the soil dries up, the leaves wither and weaken, requiring the application of irrigation to prevent their death.

Pruning

Maintenance or training pruning is not necessary when growing Begonia rex. It is only important to remove dried flower scales and wilted or diseased leaves in order to maintain a healthy microclimate around the plant.

Diseases

Leaf spot (

Saprophytic soil fungus that affects the foliar area of ​​begonias. Symptoms appear as circular brown spots with light colored edges, both on the upper side and underside of the leaves.

Gray mold (

Phytopathogenic fungus whose symptoms are manifested as rotting at the base of the stems or grayish spots on the underside of the leaves. The incidence of the pathogen occurs in humid environments and penetrates through wounds caused by insects or physical damage.

Powdery mildew (

It is a common disease in potted begonia crops that reduces the commercial quality of the plants. Dusty white or gray spots appear on the surface of the leaves, the tissues dry out and finally die.

Stem rot (

Over-watering leaves and stems creates the right environment for this pathogenic fungus to appear. Usually the fungus destroys the stem tissues, they blacken and later rot. It is advisable to destroy the affected plants and discard the substrate.

Bacterial spot (

Bacterial disease that causes rotting of stems and leaves. Symptoms appear as oily spots that rapidly destroy tissues. It is advisable to remove infected plant material.

Mosaic virus

Mosaic virus is a generic disease that can cause commercial damage to begonia plants. The characteristic symptoms appear as discolored spots of irregular shape that quickly necrotize destroying the leaf area.

References

1. Begonia rex. (2019). Wikipedia, The Free Encyclopedia. Recovered at: es.wikipedia.org
2. Morales Alvero, C., Calaña Naranjo, JM, Corbera Gorotiza, J. & Rivera Espinosa, R. (2011). Evaluation of substrates and application of arbuscular mycorrhizal fungi in Begonia sp. Tropical Crops, 32 (2), 17-22.
3. Portillo, G. (2018) Begonia rex. Gardening On. Recovered in: jardineriaon.com
4. Recasens Pahí, LR (1987). The Begonias. Begoniaceae family. Horticulture: Magazine of horticultural industry, distribution and socio-economics: fruits, vegetables, flowers, plants, ornamental trees and nurseries, (35), 9-46.
5. Schoellhorn, Rick (2002) Recycling the Rex Begonia. Vegetative Matters. University of Florida.
6. Uhl, R. (2015) Rex Begonia: Shadow King Series. Culture Connection. Crop Culture Report.