Broccolini (original Japanese: ブロッコリーニ) is a green vegetable similar to broccoli but with smaller florets and longer, thin stalks.Often misidentified as young broccoli, it is a hybrid of broccoli and kai-lan, both cultivar groups of Brassica oleracea.rom Wikipedia, the free encyclopedia. Broccolini (original Japanese: ブロッコリーニ) is a green vegetable similar to broccoli but with smaller florets and longer, thin stalks. Often misidentified as young broccoli, it is a hybrid of broccoli and kai-lan, both cultivar groups of Brassica oleracea.