This is Pueraria lobata var. montana 葛麻姆 which is very close to P. lobata var. thomsonii 粉葛 and P. phaseoloides 三裂葉野葛
P. lobata var. montana has more and packed flowers in the inflorescence, legume or pod 莢果is a bit more swollen while lobata var. thomsonii has less flowers 。 Flower colour of P. phaseoloides is pale purple or lilac but P. lobata var. montana is purple.