The genus Begonia is one of the largest groups of flowering plants, encompassing thousands of species and countless hybrids that display tremendous diversity in size, color, and texture. Identifying a specific begonia can be challenging due to this variability, but the process becomes manageable by focusing on distinct physical traits. A practical approach involves first determining the plant’s foundational growth habit before examining the details of its leaves and stems.
Understanding the Primary Growth Habits
The most fundamental way to classify begonias is by observing their underground structure and overall growth pattern, which typically fall into three distinct categories: fibrous-rooted, rhizomatous, and tuberous. Determining this habit is the first and most informative step in the identification process.
Fibrous-rooted begonias possess a conventional root ball composed of numerous thin, thread-like roots. This structure supports continuous, non-dormant growth throughout the year, provided environmental conditions remain favorable. The roots appear dense and interwoven, lacking any large, fleshy storage organs at the base or near the soil line.
Rhizomatous begonias are characterized by a thickened, creeping stem, known as a rhizome, which grows horizontally along or just beneath the soil surface. This modified stem serves as a storage organ for water and nutrients, allowing the plant to survive periods of stress. The rhizome is often scaly, fuzzy, or segmented and is typically visible at the soil line. Plants in this group often have large, showy foliage emerging directly from the rhizome.
Tuberous begonias are defined by the presence of a fleshy, rounded, or disc-shaped structure called a tuber, which develops underground. This adaptation allows the plant to enter a seasonal dormant period, during which the above-ground foliage dies back completely. Identification is confirmed by examining the base of the plant, especially during the dormant season, to locate the solid, potato-like tuber. This growth habit is most frequently associated with begonias grown primarily for their large, spectacular flowers.
Visual Clues in Foliage and Stem Appearance
Once the basic growth habit has been established, the next step involves examining the specific visual details of the leaves and stems to narrow down the classification. Begonia leaves exhibit a remarkable range of shapes, often providing immediate clues to the plant’s identity.
A common leaf type is the asymmetrical, pointed shape known as the “angel wing,” which is strongly suggestive of certain fibrous-rooted varieties. Other groups may present leaves that are deeply lobed, resembling a star or a maple leaf, or those that display a unique spiral where the petiole attaches to the blade. Examining the leaf surface texture is also informative, as some leaves are smooth and waxy, while others may be heavily felted or covered in fine hairs.
Foliage color and patterns offer further distinction, ranging from solid green to complex variegation involving metallic silver, deep burgundy, or neon green zones. Rex begonias are highly prized for their intricate patterns and often display a colorful metallic sheen. The specific arrangement of these color zones can often match known cultivars within the broader groups.
Stem structure provides another set of useful identifiers, particularly in distinguishing between upright and trailing forms. Some fibrous-rooted begonias, known as cane types, develop stiff, upright stems with clearly visible, swollen nodes or joints that resemble bamboo. Other forms may have thick, succulent stems that store water, or feature a weak, trailing habit ideal for hanging baskets. The combination of a specific leaf shape and a distinct stem structure often points toward a single begonia group.
Key Characteristics of Popular Begonia Groups
Bringing together the observed growth habit and visual characteristics allows for the identification of the most commonly encountered begonia groups.
Cane Begonias
Cane Begonias are defined by their fibrous root system and upright, segmented stems, which often feature the distinctive “angel wing” leaf shape. These plants are vigorous growers that can reach significant heights and maintain their foliage year-round, making them popular indoor specimens. Their flowers usually hang in loose clusters and range from white to various shades of pink and red.
Rex Begonias
Rex Begonias exemplify the rhizomatous growth habit, and their identification is largely based on their elaborate foliage. These plants rarely develop tall stems; instead, they produce large, often asymmetrical leaves with striking colors, textures, and spiraled patterns. Their flowers are typically small and pale, as the breeding focus for this group is entirely on the ornamental value of the leaves.
Wax Begonias
Wax Begonias, scientifically known as Begonia semperflorens-cultorum, are compact, fibrous-rooted plants that are widely used as annual bedding plants. They are easily recognized by their smooth, rounded, waxy leaves, which are often bronze or green, and their persistent, small flowers. Their compact, mounding habit distinguishes them from the taller, cane-type fibrous begonias.
Tuberous Hybrids
Tuberous Hybrids represent the tuberous group and are primarily cultivated for their exceptionally large and showy flowers that can resemble roses or camellias. These plants are seasonal, meaning they require a period of cold-induced dormancy where the above-ground growth dies back to the fleshy tuber. They typically produce single or double flowers in vibrant colors, often hanging or cascading from the stems.