GabyThe common giant senecio is a weed often found in wastelands and along roadways. Typically, it doesn’t grow taller than 40 centimeters. However, in the mountains of East Africa, researchers have discovered a relative of this weed that can reach heights of up to 9 meters. Meet the giant tree-like senecio, Dendrosenecio kilimanjari. This plant is an endemic species of the Kilimanjaro flora—the highest mountain in Africa and a dormant volcano located in northeastern Tanzania. In other words, this plant is found nowhere else in the world.
It boasts a fantastic appearance: a wooden trunk branching out like a candelabrum, adorned with lush flower clusters at the tips of each branch. What do we know about this incredible plant? The giant senecio resembles something between a pineapple and a cactus. This remarkable species colonized the slopes of Africa’s tallest mountain about a million years ago and has not been spotted anywhere else since. Dendrosenecio kilimanjari thrives at altitudes ranging from 2,800 to 4,000 meters, where it receives enough rainfall to survive, as guides from Tranquil Kilimanjaro shared.
These plants have adapted well to mountainous conditions. Specifically, they have developed water storage systems and a protective covering made of dead leaves. At the base of Kilimanjaro, the climate is hot and humid, according to Live Science. However, at the summit, which reaches 5,895 meters above sea level, temperatures can plummet to minus 29 degrees Celsius. Experts note that “the mountain creates its own weather”—with scorching sun, snow, rain, and biting winds. Moreover, the weather varies at different elevations and changes with the seasons.
The giant senecios have evolved to cope with this unpredictable climate. Their thick stems are crowned with a canopy of sturdy leaves covered in fine hairs, which help limit water evaporation from the plant. The stems and leaves store water for the dry periods, which typically occur from December to March and from June to October. These plants have adapted well to a wide range of temperatures. When their leaves die, they fold around the stem, creating a thick layer of insulation against the cold. Additionally, giant senecios produce “antifreeze” compounds that prevent ice formation in their tissues.
Most giant senecios are not much taller than a person, but some can reach heights of 6 to 9 meters. Their vertical growth is another adaptation to Kilimanjaro’s conditions, as taller plants receive more sunlight. Each year, giant senecios grow between 2.5 to 5 centimeters, meaning that the tallest specimens could be at least 100 years old.
According to a genetic study by botanists published in the journal PNAS, Dendrosenecio kilimanjari is pollinated by insects that visit the plant’s yellow flowers. After pollination, the flowers transform into fluffy seed heads that the wind carries to new locations. As noted on the Kilimanjaro National Park website, giant senecios can be found on the Shira Plateau and near the Barranco Camp. Tour operators have developed special hiking routes for travelers to observe Dendrosenecio kilimanjari: the Northern, Lemosho, and Machame routes.
Experts advise that when encountering Dendrosenecio kilimanjari, tourists should be cautious not to touch or damage the plants, which provide food and shelter for birds and small mammals. Interestingly, the deep roots of these plants help stabilize the soil, slowing down erosion on Kilimanjaro.
