From 2speccers2tools wiki

While the Jello Spite Leaf did well for itself, its complete reliance of spite meant it was restricted from getting relatively big as relying upon spite alone for energy is less efficient the bigger something is. This all changed when some populations developed pigments within their cells that allowed them to get some energy from sunlight. Because they can now rely upon spite AND photosynthesis for energy, these populations of Jello Spite Leaves were able to become much larger and soon quickly diversified. As some of their spore-like gametes got taken into the atmosphere by strong winds and ended up on passing Radons, these descendants of the Jello Spite Leaf were able to spread around the world and become an entirely new taxon in the process known as Spiteweeds.

Much like their ancestor, the Spiteweeds are multicellular organisms that do get a good amount of their energy from spite(though they no longer solely rely upon it). The large, leaf-shaped appendage every species possess helps to gather a larger amount of said spite from the air around them, though most species have multiple leaves for a greater surface area to collect more spite. Unlike their ancestor, however, this genus group also gets their energy from sunlight and the leaf-shaped appendages not only means a larger surface area to collect spite but also a larger surface area to get more light for photosynthesis. Since they can rely upon photosynthesis as well as spite to obtain energy to survive, the Spiteweeds are able to become much larger than their ancestors with the largest species often relying upon photosynthesis for energy rather than through spite. Since the genus group has long lost the ability to float through methane, the Spiteweeds have taken the root-like base of their ancestor and taken it up to 11 with a full root system. Not only does this adaptation further help provide stability so they don't get knocked over, but the Spiteweeds have also started to take in nutrients from the soil to aid in their photosynthesis. Much like their ancestor, all species in the genus group still contain high amounts of spite in their tissues that are used to deter most predators from eating them.

Since they were able to get their energy from both photosynthesis AND by taking in ambient amounts of spite, the Spiteweeds were more efficient than their ancestor and so they have driven the Jello Spite Leaf to extinction. Their spread out of Oofle has also had consequences on other species as well, and they would prove to be the final nail in the coffin for the already rare Sphere of death since this species was outgunned by more efficient descendants in either part of its diet(with the Sphere of imminent doom and their descendants being better at hunting sophonts while species like the Spite Jellies and descendants of the Jello Spite Leaf were more specialized for getting their energy from spite) and thus the last sphere of death populations died out.