When I first wrote this section in 2005, it was rather short. The reason for this was that there was limited information available on Werner, and none for Maria. At the time most sources said of the pair 'Life history unknown', though some helpfully added that they were 'two of Germany's top artists'. I was able to add birth and death dates for Werner, but that was it; the rest was speculation and educated guesswork.
Twelve years later, the amount of data accessible via the web is vastly greater, though the task of finding it has, perhaps, become more difficult. However, partly by diligent research and partly by chance, more information has come to light, which is given below (here I must acknowledge the assistance of my sister, who was able to 'flesh out' some of the snippets I gave her). The following information is taken from correspondence with the family and from scans of original documents, unless otherwise noted.
Full name: Franz Hermann Wilhelm Werner Heudtlass
Born: 27 March 1898, Berlin
Died: 26 November 1949, Berlin
Father: Julius Albert Eugenius Heudtlass (1865-1925/6, occupation, lawyer)
Mother: Auguste Helene Martha Heudtlass
Sibling: Willy Heudtlass (journalist and author, born 27/01/1901, Berlin; died 11/11/1987, Hamburg)
Married: (unverified) Maria von Axster, after March 1925, Berlin (Maria reverted to her maiden name late February, 1925). There is as yet no evidence that Werner and Maria were married, but they certainly formed a business partnership in 1925.
Occupation: Artist/illustrator, active c1924 to 1944 (possibly to 1949, see '...filling in the gaps...' below). In partnership with Maria c1925 to 1944/1949.
Children: None known.
Maria von Axster
Full name: Maria Victoria Thekla Edler von Axster (on her 1917 marriage record, she signs her name as 'Maria Victoria Thekla Edler von Axster-Uhlár' and is described as the 'adoptive daughter' of Paul Uhlár; until 1919 'Edler' was the lowest rank of nobility in Austria-Hungary and Germany (Wikipedia)).
Born: 25 March 1884
Birthplace: Linz, Austria (descended from 'an old family of Austrian officers' (source))
Died: 1966, Berlin (source)
Siblings: Possibly four (not yet confirmed)
Married: (1) Heinrich Julius Georg Altrichter on 6 December 1913 in Berlin; (2) Karl Ludwig Johannes Kabelmann on 4 October 1917 in Berlin (under her first married surname of Altrichter; a note added to the certificate suggests they divorced mid-1924); (3) (unverified; see note above) Werner Heudtlass, after March 1925, Berlin.
Occupation: Teacher of painting (c1917 to ?); Painter/illustrator (active 1905 (earliest reference, reported in Grazer Tagblatt as part of an art show) to 1944 or 1949 (last references)). In partnership with Werner c1925 to 1944/1949.
Children: None known.
An Italian site has scans of an article about the pair that appeared in Das Magazine in June 1941 (the article, in German, is light on biographical detail, though still of interest).
From here on in, the rest is more speculative, connecting disparate pieces of information gathered from the internet and books. It would seem that 'von Axster-Heudtlass' was, in fact, a joint nom de plume for Werner and Maria. Both were artists, and there is at least one poster (for the German National Railways dating from 1927) that is simply signed 'von Axster'. Another poster, also from 1927, is signed 'Axster-Heudtlass', but this is in a block script, quite unlike the signature that appears from 1930 onwards. Werner and Maria are both credited individually with posters for the National Railways, and this could be the initial connection between them (though the dating of these posters might be too late). The earliest poster bearing the signature 'von Axster-Heudtlass' appears in early 1926 (in a different style to that used from 1930 onwards). The last items found bearing the 'vAH' signature were a series of stamps issued in May 1944 (a 1949 stamp is credited to 'von Axster-Heudtlass', but bears no signature – see below).
Looking at the variety of work between the mid-1920s and 1944 does suggest more than one hand at work (compare particularly the treatment of faces), and it seems possible that both produced work under the one name. Based on the styles of work, I would suggest the the propaganda posters of c1938-1944 are the work of Werner; the landscape scenes of the mid-1930s seem more closely related to the 1927 poster credited solely to 'von Axster' (i.e. Maria). There are at least three paintings credited to Maria from before her possible marriage to Werner, two of which are landscapes. Limited information on several stamp sites suggest that, in the latter years at least, Maria was concerned with the design, and Werner with the execution, of jobs.
Only one potential example of their work is apparent after 1944, and that is for the 'Export Messe Hannover' stamp produced in April 1949. Although credited to 'von Axster-Heudtlass' by several sites, the stamp is missing any sort of signature, though the style is similar to earlier works. Two further post-1944 items are often noted on poster sites, these being Steinway advertising posters. While often dated to 1949, other sources suggest the much earlier date of 1933. However, they date from 1927 (as credited by Deutsche National Bibliothek); a similar composition is shown in Modern Publicity (January 1928). The incorrect 1949 date could be derived from Werner's death in that year. There is also some suggestion that the Steinway posters were created in France, rather than Germany, though there is no evidence Werner or Maria were active in France.
The samples given on this site are likely only a small proportion of those actually created. Since much of von Axster-Heudtlass' work was based around posters, it is likely that much of their output has now been lost. Posters in this era had a life measured in months, and those that have survived probably did so purely by chance. Obviously work that appeared in magazines is more likely to have survived, though stamps and postcards also had a reasonable survival rate given that such material was often kept by the recipients (and is now actively collected).
A side note on spellings: 'von Axster-Heudtlass' is the correct spelling (see the signature at the top of the page – the 'ß' represents a double 's' in German), but there are several variants on the internet – 'von Axter-Heudtlass', 'von Axster-Hendtlass', 'von Axter-Hendtlass' and 'von Axster-Heudtlab' are the more common. Axster-Hierstafs is one of the more unusual interpretations found.