Plant Kingdom starts the first proper set of levels in Sonic Rush Adventure. Sonic starts on the beach and shortly runs into an untamed jungle filled with enormous plants and fungi, as well as shallow streams that introduce the water mechanics of the game.
After Tails completes the Wave Cyclone, he and Sonic contemplate the possibility of finding more Material to construct bigger vessels. Marine, eager to give their new creation a whirl, insists that they head over to the island where Plant Kingdom takes place. With Sonic also ready to try out the Wave Cyclone and Tails curious as to what new Material could lie at their destination, the trio agree to travel there right away.
After arriving in this strange, botanic realm, Marine excitedly scouts around (despite Tails' insistence to be careful). Finding mushrooms bigger than her house, the raccoon chatters about how they should call the place Marine Island - oblivious to the heroes' disinterest. Sonic and Tails decide to explore the new-found island, to investigate where exactly they are. After finding and defeating a large Tyrannosaurus Rex robot, Sonic unites with Tails and Marine, bringing with him the new Green Material. They meet Tabby, a friend of Marine's, who reports sighting a mechanical island to the southwest. Sonic and Tails resolve to travel to this newly discovered location right away.
- Giant mushrooms - Functioning much like the fungi of Mushroom Hill Zone, the player bounces off the surface of these mushrooms. They are, however, much wider than their predecessors. Orange ones bounce the player upward and pink ones bounce the player at a roughly 45° or 315° angle. After bouncing off of any mushroom the player is free to perform tricks.
- Tree stumps - A short and simple obstacle visually and functionally identical to the stumps found in Leaf Storm. Boost through or jump on them to clear the road.
- Swinging bars - An organic-looking set of swing bars, which continuously spin the player about in a circular motion. Release from them at the angle Sonic or Blaze's feet are facing by pressing a jump button.
- Stem tubes - Large plant stems which suck up the player at one end, transport them along the length of the tube, and launch them out of the other end, along with a burst of pink flower petals. The player can perform tricks after being launched out.
- Humanoid trees - Trees with humanoid faces. They're scoop the player up with their unusually flexible limbs and toss them sky-bound. The player can perform tricks once released.
- Swinging vines - Hanging vines that swing left to right and back again. Often used to clear gaps. Release by pressing a jump button. Appear to be exclusive to Act 2.
- 3D trio of rails - After hitting a blue spring in Act 1, the player is situated on the middle of a trio of forward-oriented rails. Switch between rails with the left and right d-pad and jump by pressing a jump button. Aim to gather rings but avoid approaching spiked balls. This segment ends shortly and deposits the player near the level-ending treasure chest.
- Pink triceratops robots - Patrol a small area, but charge the player when approached. Most similar to Sonic 3's Rhinobot.
- Blue pterodactyl robots - Fly about a small area and swoop towards the player when approached. They tend to hang around mushrooms and other areas where you can't readily get into an offensive position, so watch out.
- Yellow piranha robots - Leap towards you in an arc as you run across the surfaces of low-lying streams. If you're not using Burst Dash they tend to leap over you, and if you are in Burst mode they'll be destroyed, rendering them as rather ineffectual adversaries.