Syngonium 'Silver Pearl' has bright silver foliage. It is bright and will add a serious pop of colour to your terrarium.
It stays very bushy and compact and requires basically no maintenance - the odd trim back every so often but there will probably be no need unless it's in a tiny terrarium. It is very easy going which makes it perfect for both open terrariums and closed terrariums.
A very easy going choice that is very happy in terrariums.