Alfalfa (Medicago sativa) or Lucerne is a legume that can be used as a cover crop mix, to fix nitrogen, to provide organic matter and also because it is also apparently a source of Boron, a mineral element vines (and other plants) need. Lucerne is also said to grow well where dandelions also thrive (Philbrick & Gregg: 1966, p.3).

Growth habit: 12-30 inches in height. Pale-purple pea-like flowers on small conical spikes (Hessayon: 2012), p.110.