The "spade-shaped" plant is similar to the arrowhead vine as to the stem and the manner it creeps. It is similar to the pothos in some ways - the leaves are light green to yellow green, but never dark green, and thinner than pothos leaves. It is much like the leaves of the arrowhead in texture. It is propagated by cuttings and one thing, the size of the leaves and its color never change through the years its in my old garden. Here, it is normally grown in pots with a pole for it to hold on and climb or planted in a large dish with other plants ( terrarium ). I will try my best to help identify the plant as its precisely the reason why i got into your webpage.