A study at Taipei Medical College, Taiwan, revealed that the Chinese herb, Cornus officinalis (shan zhu yu), can enhance the motility of human sperm and may, as a result, help infertile couples. A 68% increase in sperm motility was observed in vitro. 

Jeng H, Wu CM, Su SJ, Chang WC. ‘A substance isolated from Cornus officinalis enhances the motility of human sperm’. Am J Chin Med. 1997; 25(3-4):301-6. 

In a Chinese study, the effect of tu si zi, xian mao and ba ji tian on sperm motility was compared in vitro.  The tu si zi decoction showed the most marked improvement in sperm motility, followed by xian mao.  The effect of Ba ji tian was relatively poor. It was suggested that tu si zi may be beneficial to treat male sterility as well as raise the success rate of ART. 

Peng SJ, Lu RK, Yu LH. ‘Effects of semen Cuscutae, rhizoma Curculiginis, radix Morindae officinalis on human spermatozoan’s motility and membrane function in vitro’ Zhongguo Zhong Xi Yi Jie He Za Zhi. 1997 Mar; 17(3):145-7.