I am only a modest amateur botanist, but I find this "bible" fantastic. Although very technical in its first pages, or pages explaining the "keys" can deepen his knowledge if only one is motivated. The descriptive pages of the species are in two parts: on the left: a line drawing a superb finesse, with scale in cm and mm. There is no color, obviously (And although this is seen does not matter) right: etymology of terms, common names, distribution, etc. etc. These books are expensive, but this is normal, given the amount of information and number of pages (+ 2400!)
