50 Days to maturity. Brassica rapa Chinensis group. Taisai Pak Choi (Bok Choy) Seeds. Cool-Warm Season Annual Heirloom. The leaves of this popular and vigorous pak choi or choy sum are glossy green and distinctly spoon-shaped. Tender, crisp, white petioles are long and thick. The 18” plants are taller and less compact than Chinese pak choi types. ~ 12,000 seeds per oz.