Red Bush was added in Beta 30.0, but was changed quite a few times in its first few hours. Previous Versions can be found here.
Since Beta 51.1, Red Bush is a 3G 1/4 Plant with Transparency and an Aura effect of having its ATK changed based on other ally Plants on your board. Since Beta 54.1, it will gain +1 ATK for each one. And even though it's a Plant itself, it won't include itself, meaning its ATK will be 1 if you lack any other Plant.
Due to Transparency, it's unable to be silenced by most cards, which makes it much more likely to survive at least until your next turn, when it can attack. If played correctly, it's able to bring its own ATK up to 4 before initiating the attack, without even including effects of other cards.
You can also place down more Red Bushes. While they don't affect themselves, they do affect each other.