There was a really great book just published called "The Tea Horse Road: China's Ancient Trade Road to Tibet."
I would link to it on Amazon, but I don't have linking privileges yet.
It's written from the perspective of an ethnobotanist studying both the ancient history/culture of the pu'er trade/cultivation and its relation to trade, area politics, culture, etc. You might be more interested in the first couple of chapters, but the whole thing is both 1) gorgeous 2)scholarly and really well-researched.. not just hearsay 3) easy and enjoyable to read. Plus, you'll learn about pu'er's connections to local religion, the history of the Tubo Empire/Tibetan Autonomous Region/Akha/Yunnan/China trade tangled nut, horses, butter tea..
So it's not dry at all, but it gives you as much and more cool info yo might expect out of a textbook (as opposed to just being a pretty coffee table book with great pictures... which it also is).
It also has a great/intense bibliography which could point you to other useful English texts on pu'er and the general subject.
Some selected sources, in case you wanted to skip right to that:
Ahmed, S. A cup of diversity: Learning from the farmers of forest tea-gardens
Resurgence 250, 2008
Chen, J, Pei, S. Studies on the origin of tea cultivation
Acta Botanica Yunnanica 25,5, 2003
Huang, G. An Overview of Pu'er tea culture
Yunnan Min Zu Chu Ban She, Kunming, 2005
Long, S, Li, Y, Wang J. Traditional tea-garden systems in Xishuangbanna
In Biodiversity in Swidden Agrosystems in Xishuangbanna
Pei, S & Xu, J, editors. Yunnan Education Press, Kunming, 1997
Mair, V, Hoh, Erling. The true history of tea. Thames & Hudson (London), 2009
Purdue, PS. Is Pu-er in Zomia? Tea cultivation and the state in China
Yale University Agrarian Studies Colloqium, New Haven, 2008.
Toleno, R. A critical ecology of Akha tea cultivation in the Bulang mountains of China: The Case of Buljalpuxeevq. Thesis, University of Hawaii, Honolulu, 2006
Ton, L. Chinese tea: A cultural history and guide
China Intercontinental Press, 2005