Yes, A Rosemary hair growth study:
Rosemary: Japanese researchers have recently published a study in the “Phytotherapy Research” Journal in April 20th.
What has gotten our attention on this particular study is hair regrowth. Many people suffer from testosterone induced hair loss (androgenic alopecia), one of a couple of ways men (and some women) loss hair as they age. In this study, animals where provided a testosterone treatment to interrupt normal hair growth. 
Rosemary hair growth
A small treatment of Rosemary extract (Rosmarinus officinalis) extract, at about 2mg a day per mouse… improved hair regrowth caused by the testosterone interruption as well as dorsal shaved areas of the mouse.
The results suggest that topical rosemary hair growth extract seems to inhibit the binding of dihydrotestosterone to androgen receptors. It is because of this that the scientists believe that the Rosemary hair growth extract is a promising crude drug for hair growth.
The rosemary hair growth extract has not been tested on people, but it is a promising study regarding hair growth possibilities using a natural plant.
The study can be purchased from Wiley: