45 days to maturity. Brassica juncea var. linearfolia. Kobu Horned Mustard Seeds. Non-GMO, cool-season, annual, heirloom. This Chinese mustard is a vigorous grower with bright green, frilled leaves and classic pungency. The rare plant species forms a distinct "horn" in the center of its leaf midribs. This native of Southern China also has stellar resistance to low temperatures and matures faster than other stem varieties, making it perfect for many different growing locations. ~18,400 seeds / oz.