Aramaki, better known by his alias Ryokugyu, is an admiral in the Marines. He attained his rank during the two-year timeskip, along with Fujitora, both filling the two admiral vacancies left by Kuzan, who had resigned from the Marines, and Sakazuki, who had been promoted to fleet admiral.
Ryokugyu ate the Mori Mori no Mi, a Logia-type Devil Fruit that allows him to create, control, and transform his body into plant life. The plants he creates can be grown rapidly and moved around freely, seemingly not being limited by any rigidity that some plants, such as trees, normally possess.
Ryokugyu can generate large quantities of plants to unleash overwhelming large-scale attacks. Additionally, his plants can rapidly absorb any liquid they touch, which includes dehydrating living creatures after impaling them, leaving them as shrivelled husks.
It has also been shown that ordinary grass, trees and flowers grow in Ryokugyu’s wake, on any surface he touches, resulting in him leaving behind a trail of plants wherever he walks. It is currently unknown if this effect on his surroundings is passively active or something he does on purpose.
In the recent SBS Vol. 106 Oda confirmed that Aramaki is capable of photosynthesis:
Question: “About Aramaki, he said back in chapter 905 that he hasn’t eaten in 3 years because it’s a pain in the butt, which means because he’s the forest he’s capable of photosynthesis. As long as he gets nutrients he doesn’t have to eat! Is that right?”