Savannas are dominated by grasses, with scattered trees and shrubs spread across a landscape that typically has between 10 and 80 percent canopy cover. These tropical and subtropical grasslands receive roughly 500 to 800 millimeters of rain per year, enough to support woody plants but not enough (or too seasonal) to form a closed forest. The result is a distinctive mix of drought-tolerant, fire-resistant species found across Africa, South America, Australia, and parts of India.
Grasses: The Foundation of the Savanna
Grasses make up the bulk of savanna vegetation. In humid tropical savannas, perennial tussock grasses account for 75 to 90 percent of all aboveground plant material. A typical savanna grass community contains 10 to 15 species, though a handful tend to dominate. In West African savannas, for example, the most common species include Andropogon, Hyparrhenia, and Loudetia grasses, which form dense clumps that can grow over a meter tall during the wet season.
What gives savanna grasses their competitive edge is the way they photosynthesize. Nearly all savanna grasses use a specialized photosynthetic process (called C4) that works like a turbocharger for capturing carbon dioxide. Their cells concentrate CO2 far more efficiently than most other plants, which means they can keep photosynthesizing at high temperatures and under bright sunlight without wasting energy. This system also helps them use water more efficiently. Under mild drought conditions, savanna grasses actually widen their advantage over plants that lack this mechanism, because they can keep their pores partially closed to conserve water while still pulling in enough CO2 to grow. The tradeoff is that this system costs extra energy in cool weather, which is why C4 grasses thin out as you move toward cooler climates.
Trees That Define the Landscape
Savanna trees are spread widely enough that sunlight reaches the ground between them, feeding the grasses below. The species vary by continent, but they share common traits: deep root systems, thick bark, and the ability to survive fire and drought.
In African savannas, acacias (now reclassified under the genus Vachellia and Senegalia) are among the most recognizable trees. Their flat-topped canopies are iconic on the East African plains. Baobabs, with their massive swollen trunks that store water, can live for over a thousand years and are found across drier savannas in Africa, Madagascar, and Australia. Eucalypts dominate Australian savannas, while in South America, the Cerrado (the world’s largest tropical savanna) hosts an extraordinary diversity of woody plants.
The Brazilian Cerrado alone contains an estimated 12,000 plant species, with more than a third found nowhere else on Earth. Among these is the pequi tree, a culturally and economically important species whose oily fruit is a staple in regional cooking. Another endemic plant, known as “golden grass,” grows widely across the Cerrado and is harvested to make traditional handicrafts.
How Savanna Plants Survive Fire
Fire sweeps through most savannas every one to five years, and the plants that live there have evolved remarkable ways to handle it. For trees, the single most important defense is bark thickness. Research in Australian tropical savannas found that fire-related stem death was low (under 10 percent), and the likelihood of a tree’s aboveground stem being killed correlated directly with how thick its bark was, not with how tall or wide the trunk grew. In other words, height and diameter only help insofar as they come with thicker bark.
Different species take different paths to building that protection. Some invest in growing tall quickly, raising their buds above flame height, while others grow wide and stocky with especially thick bark. Eucalypts take a unique approach: they have buds embedded deep within their wood, so they can resprout along the trunk even after fire strips off the outer bark. This lets eucalypts get away with thinner bark than other savanna trees, freeing up energy for rapid height growth instead. Among shorter stems (around one meter tall), up to 37 percent experienced topkill from fire, while stems five meters or taller lost their tops only about 11 percent of the time.
Grasses survive fire even more simply. Their growing points sit at or below ground level, so flames consume only the dry leaf blades above. Within weeks of a burn, fresh green shoots emerge from the base. Some grass species go further, actually requiring fire to reproduce. In Brazilian savannas, smoke exposure boosted germination rates of Aristida recurvata seeds from 28 percent to 93 percent in dark conditions. Heat shock alone also promoted germination in this species. These plants have evolved to treat fire not as a catastrophe but as a signal that conditions are right for new growth.
Defenses Against Grazing Animals
Savannas support some of the world’s largest populations of herbivores, from elephants and giraffes in Africa to capybaras in South America. Plants that can’t defend themselves get eaten to the ground, so savanna species have developed both physical and chemical deterrents.
Acacias are the classic example. Many species produce long, sharp thorns that can reach several centimeters, making browsing painful and slow for even large animals. Younger trees invest more heavily in thorn production than older ones, which makes sense: a sapling can be killed by a single browsing event, while a mature tree can afford to lose some leaves. When browsing pressure increases, acacias ramp up thorn growth further, suggesting the defense is flexible and responsive rather than fixed.
Chemical defenses like tannins (bitter compounds that make leaves harder to digest) are also present, though research on desert acacias found that tannin production didn’t increase as clearly in response to browsing as thorn growth did. Only under very heavy browsing pressure did one species show signs of boosting its chemical defenses. This suggests that for many savanna trees, physical armor is the primary line of defense, with chemical compounds playing a supporting role.
How Rainfall Shapes What Grows Where
The balance between trees and grasses in a savanna shifts with rainfall. At the drier end of the spectrum, around 520 millimeters of rain per year, drought years can strip away tree cover entirely, pushing the landscape toward open grassland. Once trees disappear, grasses compete so aggressively for water and fuel fires so frequently that trees struggle to reestablish even when rains return.
At higher rainfall levels, around 780 millimeters per year, savannas become more resilient. Trees can better withstand dry spells, and the mix of trees and grasses tends to be more stable over time. Push rainfall much higher and you cross into tropical forest territory, where the canopy closes and shade-intolerant savanna grasses can no longer compete. This rainfall gradient explains why you can drive across a region and watch the landscape shift from open grassland to scattered-tree savanna to dense woodland over a span of just a few hundred kilometers.
Other Notable Savanna Plants
Beyond the dominant grasses and trees, savannas host a range of other plant types that fill specific niches. Shrubs like Combretum species form dense thickets in African savannas, particularly in areas recovering from disturbance. Wild flowering plants, including various legumes, bloom during the wet season and fix nitrogen in the soil, enriching it for surrounding plants. Palms are common in wetter savannas, particularly in South America, where buriti palms line waterways and provide food for wildlife.
Succulents like aloes and euphorbias appear in drier savannas, storing water in their fleshy leaves or stems to survive months without rain. Epiphytic plants (species that grow on other plants) are rare in savannas compared to tropical forests, since the open canopy provides little shade or moisture. The plant community as a whole is shaped by the constant interplay of fire, drought, grazing, and soil nutrients, producing a biome that looks simple from a distance but contains thousands of species finely tuned to one of Earth’s most dynamic environments.