Tupa kerstenii Vatke Lobelia deckenii is a species of flowering plant in the family Campanulaceae.

Each rosette grows for several decades, produces a single large inflorescence and hundreds of thousands of seeds, then dies.

The lobelia species on Mount Kenya are both pollinated by birds,[8][9] especially the scarlet-tufted sunbird and the alpine chat.

[10] This species of giant lobelia is known for the reservoirs of water held in its rosettes, which freeze at night and protect the apical meristem which is contained in a dense central leaf bud.

[11] The crescent-shaped ice cubes formed in these rosettes gave rise to the nickname, "gin and tonic lobelia".