From a botanical perspective, the genus Begonia is a vast and diverse group of flowering plants within the family Begoniaceae, comprising over 2,000 species and countless hybrids. They are primarily native to moist subtropical and tropical climates in South and Central America, Africa, and southern Asia. Begonias are largely characterized by their asymmetrical leaves (a key identifier), unisexual flowers (both male and female flowers appear on the same plant), and their growth habit, which can be rhizomatous, tuberous, or fibrous-rooted. This variation in morphology is the primary basis for their horticultural classification.
Rex Begonias are a category of rhizomatous begonias, prized almost exclusively for their spectacular and intricate foliage rather than their modest flowers. The term "Rex" refers to a specific species (Begonia rex) and its multitude of hybrids. Botanically, they grow from a rhizome—a thickened, horizontal stem that creeps along or just below the soil surface, from which roots and shoots emerge. Their leaves are their main attraction, displaying a breathtaking array of colors, patterns, and textures, often featuring swirls of silver, purple, red, pink, and green. The complex leaf patterns are a result of specialized cell structures and pigmentation, making them highly adapted for understory light conditions in their native habitats.
Tuberous Begonias (Begonia × tuberhybrida) are a group of hybrids developed for their exceptionally showy, often rose-like flowers. Their defining botanical feature is their root system: they grow from a tuber, which is a modified, underground storage organ that allows the plant to survive periods of dormancy, typically through dry or cold seasons. The plant dies back to the tuber after flowering and can regrow when conditions become favorable again. Their flowers can be single or double and come in almost every color except blue. They are photoperiodic, meaning they require short day lengths to initiate tuber formation and enter dormancy, a crucial survival adaptation.
This category includes common types like Wax Begonias (Begonia × semperflorens-cultorum) and Angel-Wing Begonias. Botanically, they are defined by their standard, fibrous root systems, similar to most common annuals and perennials, without specialized storage structures like rhizomes or tubers. Wax Begonias are compact, bushy plants with rounded, succulent-like green or bronze leaves and constant clusters of small flowers. Angel-Wing Begonias, named for their distinctive, elongated leaves that resemble the wings of an angel, are cane-like in growth habit. They produce tall, jointed stems (like bamboo canes) and pendulous clusters of flowers. Both types are valued for their continuous blooming cycle and adaptability.
Beyond the common types, other classifications exist based on growth habit. Shrub-like Begonias develop multiple stems from the base and can grow into substantial, woody plants. Rhizomatous Begonias, a broader group that includes Rex types, encompass many species prized for both leaf form and flower displays, all sharing the characteristic creeping underground stem. Finally, trailing or scandent begonias have long, weak stems that cascade or climb, making them ideal for hanging baskets. This growth form is an adaptation to compete for light in dense forest environments.
