#tree lucerne

AKA Cytisus proliferus, Diaxulon proliferus, Chamaecytisus palmensis and Cytisus palmensis, and tagasaste.

A tropical forage crop, native to the dry volcanic slopes of the Canary Islands, but now grown in Australia, New Zealand and many other parts of the world. It's becoming a bit of a problem here, actually.

Wikipedia claims that roots on the western side of the plant grow twice as fast as those on the right, but doesn't provide a citation. Those would be the shallow feeder roots, anyway - the plant also produces sinker roots that delve 10m into the soil, seeking water.