Herb Classification

In memorizing herb names and their functionalities, I find it easier to first classify or group, sometimes kind of arbitrarily, each herb into one single category. So I know the single major use of one herb before I memorize its other uses later when I have time. The following two links have fairly good classification of them.

單味藥 (single herb medicine): www.cmuh.org.tw/HTML/dept/1p10/china_pharm_first.htm
成方藥 (mixed herb medicine): www.cmuh.org.tw/HTML/dept/1p10/china_pharm_second.htm

As of this writing, their web pages still have problems displaying two symbols that mean something to them; both are shown as a question mark. According to their email to me, one is 飲片 and the other 濃縮藥.