Question: Which member of the Ascomycota (sac fungi) taxon did Annie Gravatt study?
Context: The Lahmiales are an order of fungi in the Ascomycota, or sac fungi.  The order has not been assigned to any class ("incertae sedis").  The taxon is monotypic and contains a single family, the Lahmiaceae, which in turn contains the single genus Lahmia. Cordyceps is a genus of ascomycete fungi (sac fungi) that includes about 400 species.  All "Cordyceps" species are endoparasitoids, parasitic mainly on insects and other arthropods (they are thus entomopathogenic fungi); a few are parasitic on other fungi.  The generic name "Cordyceps" is derived from the Greek word κορδύλη "kordýlē", meaning "club", and the Latin stem "-ceps", meaning "head". The pathogenic fungus Cryphonectria parasitica (formerly "Endothia parasitica") is a member of the Ascomycota (sac fungi) taxon, and is the main cause of chestnut blight—a devastating disease of the American chestnut tree that in the early 1900s caused a rapid, widespread die-off of this once plentiful tree from its historic range in the eastern United States. Ascomycota is a division or phylum of the kingdom Fungi that, together with the Basidiomycota, form the subkingdom Dikarya.  Its members are commonly known as the sac fungi or ascomycetes.  They are the largest phylum of Fungi, with over 64,000 species.  The defining feature of this fungal group is the "ascus" (from Greek: ἀσκός ("askos"), meaning "sac" or "wineskin"), a microscopic sexual structure in which nonmotile spores, called ascospores, are formed.  However, some species of the Ascomycota are asexual, meaning that they do not have a sexual cycle and thus do not form asci or ascospores.  Previously placed in the Deuteromycota along with asexual species from other fungal taxa, asexual (or anamorphic) ascomycetes are now identified and classified based on morphological or physiological similarities to ascus-bearing taxa, and by phylogenetic analyses of DNA sequences. This is a list of genera in the Ascomycota phylum of fungi with uncertain taxonomic placement (incertae sedis).  These genera have not yet been assigned to any class, order, or family.  The list is based on the 2007 Outline of Ascomycota as well as updates made in the literature since then.  Certain genera (marked as tentative) have a tentative placement in the Ascomycota, and have been placed here provisionally pending further study. Annie Gravatt (Annie Evelyn Rathbun) was an American forest pathologist.  Her areas of research included plant physiology and white pine blister rust.  She also studied Chestnut blight, the fungus that devastated American chestnut trees in the early 20th century.  Along with her husband, George Gravatt, she founded the community of Scientists' Cliffs, Maryland. Dutch elm disease (DED) is caused by a member of the sac fungi (Ascomycota) affecting elm trees, and is spread by elm bark beetles. Although believed to be originally native to Asia, the disease was accidentally introduced into America and Europe, where it has devastated native populations of elms that did not have resistance to the disease.  It has also reached New Zealand.  The name "Dutch elm disease" refers to its identification in 1921 and later in the Netherlands by Dutch phytopathologists Bea Schwarz and Christine Buisman who both worked with Professor Johanna Westerdijk.  The disease affects species in the genera "Ulmus" and "Zelkova", therefore it is not specific to the Dutch elm hybrid. Morchella, the true morels, is a genus of edible sac fungi closely related to anatomically simpler cup fungi in the order Pezizales (division Ascomycota).  These distinctive fungi have a honeycomb appearance, due to the network of ridges with pits composing their cap.  Morels are prized by gourmet cooks, particularly in French cuisine.  Due to difficulties in cultivation, commercial harvesting of wild morels has become a multimillion-dollar industry in the temperate Northern Hemisphere, in particular North America, Turkey, China, the Himalayas, India, and Pakistan, where these highly prized fungi are found in abundance. Sclerotinia sclerotiorum is a plant pathogenic fungus and can cause a disease called white mold if conditions are conducive.  "S. sclerotiorum" can also be known as cottony rot, watery soft rot, stem rot, drop, crown rot and blossom blight.  A key characteristic of this pathogen is its ability to produce black resting structures known as sclerotia and white fuzzy growths of mycelium on the plant it infects.  These sclerotia give rise to a fruiting body in the spring that produces spores in a sac which is why fungi in this class are called sac fungi (Ascomycetes).  This pathogen can occur on many continents and has a wide host range of plants.  When "S. sclerotiorum" is onset in the field by favorable environmental conditions, losses can be great and control measures should be considered. Pezizomycotina contains the filamentous ascomycetes and is a subdivision of the Ascomycota (fungi that form their spores in a sac-like "ascus").  It is more or less synonymous with the older taxon Euascomycota.  These fungi reproduce by fission rather than budding and this subdivision includes almost all the ascus fungi that have fruiting bodies visible to the naked eye (exception: genus "Neolecta", which belongs to the Taphrinomycotina).
Answer: Chestnut blight