While often associated with arid desert landscapes, cacti also thrive in Florida’s humid, subtropical environment. This may seem surprising given the state’s abundant rainfall and lush vegetation. However, Florida hosts a variety of native and naturalized cactus species, showcasing remarkable adaptation to diverse conditions.
Florida’s Unexpected Cacti: A Diverse Flora
Florida’s cactus population is more diverse than generally assumed, featuring several native species and some introduced varieties that have naturalized. The most prevalent group is the prickly pear (Opuntia spp.), recognized by its flattened, paddle-like pads. Examples include the Florida prickly pear (Opuntia austrina), found predominantly in South Florida, and Opuntia stricta, a coastal prickly pear that can reach up to 5 feet tall. Another native prickly pear, Opuntia humifusa, is widely distributed across the state, thriving in various sandy habitats.
Beyond prickly pears, Florida is home to other unique cacti. The triangle cactus (Acanthocereus tetragonus) forms thickets in coastal hammocks, growing as tall as 23 feet with large white blooms that open at night, attracting pollinators. The Simpson’s applecactus (Harrisia simpsonii) is another night-blooming native, recognized by its tall, elongated stature and bright red fruits. The mistletoe cactus (Rhipsalis baccifera), an epiphytic species, grows in the Everglades and surrounding islands, adapted to high humidity. While some barrel and columnar cacti are sold in Florida, they are introduced species rather than widespread natives.
Habitats and Distribution
Florida’s cacti are concentrated in specific ecosystems that provide drier, well-drained conditions, despite the state’s overall humidity. These include sandy coastal areas, such as dunes and coastal strands, where species like Opuntia stricta and Opuntia humifusa are common. The porous sandy soil in these areas allows for rapid water drainage, preventing root rot.
Cacti also flourish in Florida’s scrublands, scrubby flatwoods, and sandhills, which are characterized by dry, sandy soils. These habitats, often found on slightly higher elevations, mimic arid conditions due to their excellent drainage. The unique South Florida rocklands, particularly pine rocklands and tropical hardwood hammocks, also provide suitable environments for certain cacti. These areas feature limestone outcrops with thin soil layers, allowing for quick water runoff after rainfall.
Thriving in the Tropics: Adaptations of Florida Cacti
Cacti in Florida demonstrate specific biological mechanisms allowing them to thrive in a humid and rainy climate. Their most apparent adaptation is succulence, the ability to store water in their fleshy stems, or “pads” in the case of prickly pears. These modified stems contain specialized open cells, which efficiently hold water for extended periods, helping the plants endure dry spells between rain events.
Many Florida cacti also employ Crassulacean Acid Metabolism (CAM) photosynthesis. This metabolic pathway allows them to open their stomata, the pores for gas exchange, primarily at night when temperatures are cooler and humidity is higher, reducing water loss through evapotranspiration. During the day, stomata remain closed, conserving moisture while the plant processes the stored carbon dioxide. Their root systems are often shallow and widespread, enabling quick absorption of water from sporadic rainfall, while also being tolerant of the sandy, nutrient-poor soils common in their preferred habitats. This combination of efficient water storage, specialized photosynthesis, and adaptable root systems enables Florida’s cacti to successfully inhabit niches within the state’s diverse ecosystems.