The objective of this manual is to present to administrators, nurserymen and professionals operating in the field of Mediterranean forest management information on the seed biology of Mediterranean trees and shrubs as well as on the available techniques to improve germination and nursery growing. This work has been written also for students, to whom basic scientific tools for further research are provided, and, in general, is dedicated to people who deal with seeds of trees and shrubs. Twenty six authors, mostly Italian but also Australian, English, Polish and Spanish, have contributed to synthesise and amalgamate the available information, which, in part, is the result of their own work as researchers, technicians or nurserymen.
Gathering and processing data presented here was not easy because published information on how to propagate Mediterranean species is limited and nursery workers, important sources of knowledge, just do not have the time to document what they know.
More than one hundred trees and shrubs strongly characterising Mediterranean areas are examined, even if, as in a few cases, they are not natives. Those species for which information about propagation was lacking were not considered: the list, therefore, is not exhaustive and someone could be disappointed not to find a plant of particular interest. On the other hand, the text contains a number of species that are not strictly Mediterranean but normally occurring in peculiar Mediterranean micro-environments, e.g. those plants belonging to other climatic bands that for reasons linked to soil conditions and water availability may also grow in Mediterranean regions. Finally, a number of important plants like caper and licorice have been included even if not classifiable as either trees or shrubs.
Plants have been subdivided in Gymnospermae, in botanical terms species without true flowers in the division Pinophyta of the plant kingdom, and Angiospermae, trees with true flowers in the division Magnoliophyta. Within these two groups, trees and shrubs are listed alphabetically by genus. Common names are stated as well.
Information is presented as a series of fact sheets which contain the available information on collecting, storage, required pre-treatments to remove dormancy, sowing and practices to be carried out during the first growing stages. The average germination percentage and the number of seeds per kg is also provided where available. Due to the marked variability of seed size and weight, for the parameter ‘number of seeds per kg’ a range is indicated and within it, when available, the most frequent values for each species are considered between brackets.
All measurements are given in metric units.
In nursery practice, the term seed refers to any material used for sowing, irrespective of the correct botanical definition, and in this sense it has been used in the text. For example, with regard to the ash tree, seed refers to the samara, which actually is not a seed but a winged indehiscent fruit.
As they are still widespread, risky pre-treatments (immersion in hot water or soaking in acids) have sometimes been described for scarifying legume seedcoats. However recent regulations make it difficult to use corrosive substances.
A glossary of technical terms has been included to help in the comprehension of the text.
The Index Kewensis is the reference for taxonomy.