The genus Begonia is a vast and diverse group within the family Begoniaceae, comprising over 2,000 accepted species and countless hybrids. They are primarily tropical and subtropical plants, valued for their stunning foliage and flowers. Botanically, they are characterized by their asymmetrical leaves, unisexual flowers (with both male and female flowers on the same plant), and a capsular fruit with numerous tiny seeds. Their classification is complex but is often simplified for horticultural purposes based on their root structure and growth habits.
This is a fundamental botanical method for categorizing begonias, as the root system defines their growth pattern and care needs. There are three primary types:
Fibrous-Rooted Begonias: These possess a standard, thread-like root system. They are typically grown for their prolific flowers and include the ubiquitous wax begonias (Begonia semperflorens-cultorum group) and the eye-catching dragon-wing types. Their fibrous roots allow for compact, bushy growth and make them excellent bedding and container plants.
Tuberous Begonias: These plants develop a modified underground storage organ called a tuber, which is a swollen stem that stores nutrients and water. This adaptation allows the plant to survive periods of dormancy, typically in dry or cool seasons. Tuberous begonias, such as Begonia × tuberhybrida, are renowned for their spectacular, often rose-like flowers. The plant dies back to the tuber, which can be stored and replanted the following growing season.
Rhizomatous Begonias: This group grows from a rhizome, a thickened, horizontal stem that creeps along or just beneath the soil surface. Roots and leaves emerge from the top of the rhizome. This growth habit is predominantly associated with begonias prized for their extraordinary and intricate foliage, such as the famous Rex begonias (Begonia rex-cultorum group). The rhizome allows the plant to spread and form a dense clump of leaves.
Beyond their roots, begonias can be grouped by their physical form and growth pattern, which is crucial for understanding their placement in a garden or interior landscape.
Cane-like Begonias: These have erect, bamboo-like stems with prominent nodes and large, often angel-wing shaped leaves. They can grow quite tall and may require staking. A classic example is Begonia 'Lucerna' or the angel-wing begonia (Begonia coccinea).
Shrub-like Begonias: This is a broad category encompassing multi-stemmed, woody begonias that form dense, bushy clumps. They can range from small to very large and include many fibrous and rhizomatous species. Their bushy nature makes them ideal for providing a full, lush appearance.
Trailing/Scandent Begonias: These varieties have long, weak stems that cascade beautifully over the edges of hanging baskets or trail along the ground. Many tuberous begonias have a trailing habit, perfect for adding vertical interest to a garden or patio.
Thick-stemmed Begonias: A smaller group characterized by a few, very thick, often succulent stems. They tend to be slow-growing and can develop a unique, almost caudex-like appearance over time, such as Begonia dregei.
