The direct answer to whether succulents are tropical plants is generally no. The distinction lies in their fundamental biological adaptations to water availability. Succulents are defined by their ability to store water in fleshy tissues, allowing them to thrive in arid or semi-arid environments. Tropical flora is defined by the climate zone it inhabits, characterized by consistently high temperatures and typically high moisture levels.
Defining Succulents and Tropical Flora
Succulents are a functional group of plants that store water in specialized tissues, such as leaves, stems, or roots, to withstand periods of drought. This trait, known as succulence, appears across numerous plant families, including Cactaceae and Crassulaceae, and is an adaptation to dry conditions. Succulents are commonly native to deserts, steppes, and rocky areas that experience infrequent rainfall.
Tropical flora refers to plants that originate from the tropical zone, between the Tropic of Cancer and the Tropic of Capricorn. This region is characterized by warm, stable temperatures year-round and high, consistent rainfall and humidity, which supports plants with a high demand for continuous moisture.
The Primary Difference: Water Adaptation
The physiological divergence between most succulents and true tropical plants centers on their strategies for managing water loss. Most desert succulents employ a specialized form of photosynthesis called Crassulacean Acid Metabolism (CAM). This process allows the plant to open its stomata—the pores used for gas exchange—only at night when temperatures are cooler and humidity is higher.
By keeping stomata closed during the day, CAM plants significantly reduce water loss through evapotranspiration, achieving a much higher water-use efficiency than other plants. Many succulents also feature thick, waxy cuticles or reduced surface areas, like the spines on a cactus, further minimizing water loss.
Conversely, typical tropical plants use the standard C3 photosynthetic pathway, keeping their stomata open during the day to maximize carbon dioxide uptake. These plants have high transpiration rates and need continuous water uptake from the soil, an adaptation known as mesic. Their broad, often glossy leaves are designed to maximize light capture and facilitate high rates of gas and water exchange. This strategy is only sustainable in an environment with high, dependable moisture.
Succulents That Live in Tropical Climates
While most succulents originate in arid or semi-arid regions, some exceptions thrive within the geographical boundaries of the tropics. These plants are often referred to as “jungle succulents” or “tropical epiphytic succulents,” having adapted to unique niches within the tropical environment. Examples include many epiphytic cacti, such as Rhipsalis and Christmas Cactus, and certain species of Hoya.
These plants do not grow in the soil of a desert, but rather perch harmlessly on the branches of other trees, a growth habit known as epiphytic. Living high in the humid canopy, they receive filtered light and absorb moisture from the air and intermittent rainfall.
Their succulence, storing water in leaves or stems, allows them to survive the brief dry periods between rain showers or when water quickly drains from their aerial perch. Although they exist in a tropical climate zone, their specific water-conserving traits are still required due to their specific habitat niche. This makes them a distinct group from both the classic desert succulent and the typical moisture-dependent tropical flora.
Translating Climate to Care
Understanding the climate origin of a plant group directly translates into proper care. Desert-adapted succulents require infrequent, deep watering, allowing the soil to dry out completely between sessions to mimic desert rainfall patterns. They have a low tolerance for high humidity, which can lead to fungal diseases and rot.
Conversely, true tropical plants require consistently moist soil and often thrive in high-humidity environments, which is necessary to support their high transpiration rates.
Temperature and Soil Needs
Temperature is another distinguishing factor. Many desert succulents require a cool, dry dormancy period to trigger flowering or to survive the natural temperature fluctuations of their native habitat. True tropical plants, however, require consistent warmth, often above 60 degrees Fahrenheit, and can suffer damage if temperatures drop too low. The soil composition also differs, with succulents needing fast-draining, gritty mixes, while many tropical plants prefer richer, moisture-retentive substrates.