The Ritter Diaries

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Publisher: Deutsche Kakteen-Gesellschaft e. V. Bachstelzenweg 9, 91325 Adelsdorf, Germany

April 2017

Any use, in particular copying, processing, translation, microfilming, loading and processing in electronic systems – unless expressly authorized by the Copyright Act – requires the authorization of the publisher.

Collaboration (in alphabetical order):
Andreas Hofacker
Norbert Sarnes
Daniel Schweich

Translations (in alphabetical order):
Mario Borello

Graham Charles
Andreas Hofacker
Rebecca Hofacker
Wolfgang Mauersberger
Rodrigo Corrêa Pontes
Daniel Schweich

The diaries

W. SchepoksFriedrich Ritter (9 May 1898 – 9 April 1989) spent many years of his life in Mexico and South America. There he undertook numerous research trips to explore the cactus flora. He published his findings in many journal articles and in several books, but especially in his monumental work “Kakteen in Südamerika”, self-published in four volumes from 1979-1981.
During his life, Ritter published 16 new cactus genera, 812 new cacti (43 of them with other authors) and 253 new combinations. Although nowadays not all his taxa are recognized, Friedrich Ritter must be considered as one of the most important cactus researchers of the 20th century. If you are dealing with South American cacti, the name Friedrich Ritter will very soon be encountered.
The herbarium materials of Ritter have already been evaluated (EGGLI & al. 1995: Cactaceae of South America: The Ritter Collections.) There, one finds also detailed biographical notes.
In 1982, Ritter bequeathed his diaries to the local branch of the German Cactus Society, named after him, the “Kakteenfreunde Friedrich Ritter Nordhessen/Kassel“. These comprise 88 diaries and a few other documents.
The documents were handed over to the Deutsche Kakteen-Gesellschaft e. V., with the provision that they are made generally accessible in a suitable form. A loan is not permitted.
The original documents are now in the archive of the Deutsche Kakteen-Gesellschaft e. V. and the diaries were digitized by Daniel Schweich, Jonage.
With this publication, we follow the wishes of the “Kakteenfreunde Friedrich Ritter Nordhessen/Kassel” and provide the diaries to the public as historical documents.
The commercial use of these documents is expressly forbidden.

Explanation of the diaries

The diaries were created by Friedrich Ritter, supplemented and corrected over the years. They are in various states of preservation and in some cases very difficult to decipher. Ritter used pencil, fountain pen, and different coloured pens to make his notes. On several pages, for example, there are multicoloured notes, extensions and additions.
The diaries are 16 -16.5 cm high and 10-11 cm wide, a few smaller (about 13 x 9 cm) and three larger (21 x 16 cm). One is 10 cm high and 16 cm wide. These are usually notebooks or school notebooks. Probably later, Ritter has provided the diaries with continuous numbering from 1 to 5051 (gaps are also present). There are some index-diaries (diaries 75, 77, 78, 79, 80, 81, 83, 84) in which this page numbering is referred to. On these pages are listed locations with the cacti occurring there.
In addition there are 18 blank pages, 35 pages from various supplements, 2,249 pages for lists (index diaries, herbarium lists, …), as well as 2,782 pages with personal notes on life circumstances, expenses, photographic technology, etc. These 2,782 pages are not numbered and “at the back” of the respective diary.
Overall, there are 10.135 pages.
For reasons of simplification, two facing pages (with few exceptions such as the bindings) were scanned together. Nevertheless, a dataset of about 90 Gbyte has been created.
The file size was reduced and from every diary a PDF was generated. Each diary is preceded by an index.
A country-specific index was also produced.
Since the numbering of Friedrich Ritter was not consistently carried out and there was no paging at all on the pages with the personal notes, a continuous numbering for each diary was added to make it easier to find one`s way.

The easiest way to access the use of the diaries is through the index-diaries,

  • For Argentina:          Diaries 75, 77
  • For Bolivia:               Diaries 77, 80, 81
  • For Brazil:                 Diary 83
  • For Chile:                 Diaries 77, 78, 79
  • For Paraguay:         Diary 83
  • For Peru:                  Diaries 77, 84
  • For Uruguay:           Diary 83

Here are, partly ordered by collections, partly by taxa, the respective pages listed. However, it is to be expected that there are still other unseen pages and that there is additional information in the personal notes.
The character Ŧ (in this or a similar form) in the text is a reference to a continuation of the text elsewhere. Occasionally the instructions are provided with a page number.


It is intended to transcribe the diaries, which means to translate them into machine-readable form. For this we need your help. If you are transcribing individual parts or even entire diaries, we would be very much obliged if you would provide us with these transcripts. Please note that this transcription should be as unchanged as possible. Nothing should be changed or supplemented. Errors, abbreviations etc. must be preserved. The transcription will be added to the specific diary as soon as possible.
In order to make it possible to identify the pages as easily as possible, we have provided all the pages with their own numbering. Please use this numbering to identify the pages and not Friedrich Ritter’s pagination.
You can always send your processed text by e-mail to the following address:

Andreas Hofacker
President of the Deutsche Kakteen-Gesellschaft e. V.

Click here to get the Ritter Diaries