xxii 
semblance in essential characters. Some of these orders are well- 
defined natural groups whose affinities are undoubted, like the 
great families of Composite and Cruciferx ; others are more or less 
artificial, and appear to pass into each other by almost insensible 
gradations ; their limits are variously defined by different botanists, 
and are often made dependent upon obscure structural peculiarities 
only appreciable by an advanced student of the science. The Flora 
of this country is too limited to require reference to the minute and 
complex details of botanical classification, upon which the general 
arrangement of the Vegetable Kingdom has been founded ; and the 
characters given in the accompanying Table of Orders and Genera 
must be regarded as applicable only to British plants,—it being 
intended merely as a Key or Index to enable the reader to refer 
any wild plant to the Natural Order under which it is figured and 
described in this work. The British Flowering Plants are here 
arranged in the order stated below,—with few exceptions, that 
usually adopted by British botanists. 
EXOGENS. 
THALAMIFLOR&. 
1. Ranunculacee. 9. Violacez. 16. Tiliacez. 
2. Berberidacee, 10. Droseracez. 17. Hypericacez. 
3. Nymphzacee. 11. Polygalaceze. 18. Aceracez. 
4. Papaveraceze. 12. Frankeniacez. 19. Geraniacee. 
5. Fumariacez. 13. Caryophyllacez, 20. Balsaminaceze. 
6. Cruciferze. 14. Linacez. 21. Oxalidaceze. 
7. Resedacee. 15. Malvacee. 22. Staphyleacez. 
8. Cistacez. 
CALYCIFLORE. 
23. Celastraceze. 32. Portulacez. 41. Caprifoliacez. 
24, Rhamnacez. 33. Illecebraceze. 42. Rubiaceze. 
25. Leguminose. 34. Crassulacez. 43. Valerianacez. 
26. Rosaceze. 35. Grossulariacez, 44, Dipsacez. 
27. Onagracer. 36. Saxifragacen. 45, Composit. 
28. Haloragacez. 37. Umbellifere. 46. Campanulace. 
29. Lythraceze. 38. Araliacese. 47. Lobeliacez. 
30. Tamaricacez. 39. Cornacee. 48. Vacciniacce. 
31. Cucurbitace. 
40, Loranthacer, 

