2 HOW TO USE THE BOOK 



the actual specimen. To make sure of the species run through all the descriptions 

 given under one genus. This is not so tedious as it sounds, for the largest genera 

 have been split up into groups, each with a different characteristic. 



The purpose of the descriptions, therefore, is to supplement the illustrations and 

 to carry the identification as far as the species where that has not already been 

 done. With these objects, and also to save space, descriptions have been confined 

 to the salient points of difference between the species. 



The arrangement of Families is approximately that of Bentham and Hooker, 

 the system in use at Kew. 



The name of the Family is followed by the floral formula (see page 4). After 

 the floral formula is given a brief list of well-known herbaceous plants, if any, 

 belonging to the Family. (For instance, the flowers of most of the Solanaceae 

 resemble each other, and this fact may assist identification.) 



The genera belonging to one Family and the species to one genus follow each 

 other in alphabetical order, unless the Family or genus has been subdivided, in 

 which case the alphabetical order is limited to each subdivision. 



An asterisk (*) indicates that the plant is not hardy at Kew, though successfully 

 grown in the open throughout the year near the south and west coasts of the 

 British Isles. 



Generic and specific names are followed in brackets by synonyms still in general 

 use, and then by the common name or names, if any. The international rules of 

 botanical nomenclature have been observed wherever they are not likely to lead to 

 serious confusion in the minds of those for whom this book is primarily intended. 

 In order to save space and because of their limited interest, the authorities for the 

 botanical names have not been cited. For these the Kew Hand-list should be 

 referred to. 



The first figure after the name of each species shows the maximum height in 

 feet which the plant is expected to reach in these islands, given favourable con- 

 ditions. Subsequent figures give maximum dimensions in inches. The first 

 figure is followed by the months of flowering, when known. 



At the end of each description appears the country of origin. It is interesting 

 to observe that out of the 1,732 species dealt with in this book 29 per cent are 

 natives of China or Japan, 21 of North America, 20 of Europe, 7 of the Himalayas, 

 6 of New Zealand, 5 of South America, 4 of North and West Asia, 4 per cent are 

 hybrids, 3 per cent are natives of Australia or Tasmania, while only i per cent is 

 of African origin. 



It is possible that the plant looked for may be one that is unknown to the author 

 or, if known, omitted for lack of space. In either event there can, of course, be 

 no clear identification. In deciding what to omit the question has always been 

 asked : Is it worth growing or likely to be met with ? Sometimes there have been 

 other considerations: for instance, a species may owe its inclusion to the part it 

 has played in the production of well-known hybrids, or to its botanical interest, 

 or to the mere chance that the author happens to be more familiar with it than 

 with some other which may have equal claims to notice. Omissions could be 

 made good in a larger edition, should there be enough demand for one. 



