[2] He developed this further over a number of publications, including the Nixus plantarum (1833)[3][4] and a second edition of Natural History (1836), in which he introduced the concept of a higher order of taxonomic rank, the Alliances, in which he embedded the Tribes (families).
[7][8] In 1839 he revised his division of the plant kingdom into classes in an article in the Botanical Register.
[11][12][13] The schema of the Natural History is shown on pages xxxv and xxxvii-xlviii.
[15] Cross references from Natural History to Vegetable Kingdom in [Square brackets].
[27] In this work he also reviews all his previous publications relative to the many known systems published at that time.