The correspondence files are arranged alphabetically; most of them have the name of the person writing, but some files have subject titles. Some letters have been arranged in chronological files, but all have similar subjects. Mulford and Racine Foster corresponded with individuals and organizations around the world about all aspects of their business including identifying and selling bromeliads. They corresponded with experts at such institutions as the Smithsonian and Kew Gardens as well as local nurseries. The series also includes personal correspondence, Christmas cards and letters to publishers. Further correspondence with publishers may be found in its own subseries. The folder entitled "Lectures" contains arrangements for Mulford Foster to lecture not the lectures themselves, which may be found in the Lectures subseries. Correspondence between Racine and Mulford includes various other writings by them both. Some letters include photographs; Tom Lineham returned some photographs to Racine Foster within his letter and Kay Schools illustrated her letters with drawings of bromeliads.

Correspondence sometimes continued for decades, but often a folder contains only a single letter. Occasionally, both sides of the correspondence is available, which shows that Mulford and Racine frequently responded to each other's letters. Family correspondents include Racine's sisters Jeanne Denny and Florence Hall and Mulford's brothers Hubert and Preston and his sisters May Hurff and Rosena Whitlock. Notable correspondents include David Fairchild, A. J. Hanna, F. C. Hoehne, Harry Leu, Victoria Padilla and Lyman B. Smith.

Articles about Mulford Foster begin the subseries followed by work designated as urgent and list of publication. Subsequent files are arranged alphabetically by title. Not all the manuscripts were published, and the files may include the manuscript, correspondence with publishers, research notes and the published article or some combination of these materials. Where only the published article is held, it may be found in the Author Files. Most of the articles concern bromeliads or other plants, but Racine Foster wrote on other subjects and also fiction. Mulford and Racine edited the Bromeliad Society Bulletin during the 1950s and the materials for this publication include correspondence, notes and planning materials associated with the editorial role. The pineapple issue includes correspondence with and photographs from the Dole Pineapple Co.

includes articles by Michael A. Spencer as well as by Racine Foster. Mulford Foster wrote an article on F. C. Hoehne from whom there is also correspondence in the previous subseries. includes color slides of two new hybrids in "published form", Aechmea Miriam and Aechmea Jeanne Eunice. Some covers drawn by Mulford B. Foster are held with the articles that he wrote. Where there is more than one article or no articles by him in an issue, the drawings may be found under the name of the magazine.

This subseries documents the process of collecting plants. Notebooks number the plants found and these numbers are also marked on the botanical drawings so that the description and the image may be matched. Some photographs are also numbered and they are held in folders entitled "Plant Photographs". Other photographs and albums hold not only images of plants but also South American Indians, houses, markets, individuals and transport. Photographs that were loose in the back of albums were placed in a separate folder with the same title as the album. The Mexican album from the 1930s holds originals by Diego Rivera who was friend of Mulford Foster.

The Palm Notebooks document Foster's work for Fairchild Gardens finding Palm species while the Venezuela and Jamaica Travel Notebook contains more information about possible contacts than about plants. Notebooks are embellished with comments by Racine Foster and Michael Spencer. Notes concerning D. J. McGhee of Marine Studios are in the loose materials from the Mexican Notebook. Colombia notes include a scribbled map of Colombia. Correspondence in this subseries documents travel arrangements and provides details of Mulford and Racine's travels to their families and friends. In 1935, Foster visited Mexico with Tibor Patake and correspondence with him may be found with the " Correspondence" subseries. Much of the research material consists of tourist information for the places visited, and the material continued to be amassed long after the visits to those countries. Items of memorabilia include a coco bag that is pictured in some photographs and the briefcase that Foster used in Colombia.

Mulford Foster was a prolific artist who painted in a variety of media; botanical subjects predominate in his work though his paintings cannot all be described as botanical drawings. Exhibitions including one held at Florida Technological University (now the University of Central Florida) begin the subseries. Mulford associated with other artists, and the subseries includes a letter opener signed by Frederic Spigel. Racine's manuscript of an article about Mulford's art may also be found here. News clippings and brochures provide information about other artists, philosophers and performers. Photographs document most of Mulford's work; the photographs of elephants seem to have served as inspiration for one of his paintings. Finally, some of his sketches complete the subseries.

Notebooks, photographs, lists, catalogues and card indexes document Mulford and Racine's work in propagating, growing and selling plants. Mulford and Racine Foster allowed the public to tour their greenhouse and the Orchidario passes were the entry tickets. Patents include the plant labels for the plants that Foster created. Photographs of hybrids sometimes include images of the hybrids' parents as well. Correspondence regarding Richard M. Lewis's slides may be found in the " Correspondence" subseries. One notebook includes pencil drawings with occasional comments about how the plant performed; another notebook documents cultivation from 1957 onwards. Plant Photographs have the same numbers as those in the notebooks so that the descriptions and images may be correlated.

Arranged in alphabetical order, this subseries documents Mulford Foster's work in landscape design. For the Floating Islands project, Foster moved a six trunk date palm from 718 Magnolia to Leesburg, and photographs of this feat may be found here. The Marine Studios project that became Marineland, Florida includes correspondence from the main investors, such as, Ilia Tolstoy. Photographs of the landscaping in progress, the completed project and a brochure for the opening ceremony are held here. Plans for the Herlong property and photographs of Foster's landscaping work are notable in this subseries.

Mulford Foster collected a lot of information on plants much of which was kept on a series of card indexes and all these materials may be found in this subseries. Flyers, programs, notes, clippings, microscope slides and newsletters that provide information about plants especially bromeliads may all be found here. The notes include Mulford Foster's comments on Fosterella and Cryptanthus.

Photographs form a large part of this subseries; the photograph album pages include images of several types of plant including bromeliads. There are many images of bromeliads taken in various places, such as, the field and in Foster's house and gardens, for a variety of reasons, such as, identification, record keeping or publication. The folder on Hohenbergia Salzmanii holds photographs of the plant "breathing". Most images were taken by Mulford or Racine Foster but some were taken by other individuals usually for publication or identification. Black and white prints, color prints, negatives, and slides may all be found here and are arranged alphabetically. Most of the images of bromeliads are arranged alphabetically by the plant's formal name, but a few folders at the end contain more general images of bromeliads. Images of gardens follow: gardens that are well-identified are held in separate folders arranged alphabetically. Images of non bromeliad plants are also held in this subseries. Publications include a variety of magazines and periodicals, and the negatives are images of rare books on bromeliads. The reason that some images were labelled "sample photographs" is unknown.

The final subseries includes a variety of materials that are either personal or not covered by the other subseries. Designs for the Christmas cards that Mulford Foster sent out each year may be found here including woodblocks for printing one card. From 1935, the cards were from both Mulford and Racine Foster. Christmas cards that they received may be found in Series III. These items of correspondence had not been kept in the larger Correspondence subseries so they were not inter-filed. Mulford Foster was mourned by many who were interested in bromeliads, and information documenting his life and work is held under "memorials". Racine Foster held a service in his memory at Bromel-La, and the event is documented here. His own personal philosophy is documented separately in this subseries. The funeral receipt is for an infant Foster, and some news clippings are from the family newspaper. Both Mulford and Racine were interviewed on television and lists of questions they were asked may be found here.

Many photographs are held in this subseries. Of particular interest are images of Mulford and Racine Foster, their family, pets and friends, such as, Lyman Smith and Oather Von Hyning. Photographs of their properties at 718 Magnolia and Bromel-La show the buildings and gardens. Other places and properties are also represented here including Andre Smith's Research Studio that became the Maitland Art Center. Two folders of unidentified images are filed together, but a larger group of unidentified negatives, in their original containers, is housed separately.