Purple tree collards (Brassica oleracea var acephala). Plants have a habit of growing with a central woody trunk and bushy top growth and can reach more than 2m tall. They need staking for support. The leaves have an incredible deep purple colour and are used just like kale. We waited quite a few years to receive one small cutting, as these are difficult to come by in the UK. More commonly found in the USA than here. That tiny cutting has been propagated into many stock plants, this is usually done by taking stem cuttings which root really rapidly once potted up.