Brassica juncea. Sweet, slightly pungent, elegant, and rare heirloom mustard from Australia grows 10-12" tall with crinkly, light green leaves. Add fresh to salads or saute with other greens. Named as a "lettuce" because the delicious and beautiful leaves resemble many old lettuce varieties. 
 
In his book 100 Vegetables and Where they Come From, William Woys Weaver explains that this tender mustard's ancestors originated in China, and that it likely traveled to Australia during the Gold Rush, which began in the mid 1800s. He also explains that in the 1970s an elderly gardener gave this rare heirloom mustard seed to Katie Hiller of Mount Glorious, Queensland who grew it in her nursery. Rose-Marie Lacherez subsequently named this variety for Katie.