75-80 day maturity. Vigna unguiculata subsp sesquipedalis. Purple Mart Tsu In Yard Long Bean Seeds. Non-GMO Warm-Season Annual Heirloom. Purple Mart Tsu In Beans have been cultivated for centuries in India and China. This variety is desirable for its rich deep dark purple-colored pods. A generous producer of about 20" long beans weighing around 40 grams. The beans are tender and stringless with dark purple coloration that turns black when cooked. Try planting arugula at the base and interplanting with bitter melon vines for increased pest resistance, faster growth, and efficient use of space. Approx. 180 seeds per oz.