Engineer and amateur botanist, gardener and local historian, Jellett is known for his various books about Germantown, its environment, gardens, old homes and residents of the area. He was very active in the Germantown Horticultural Society and in the Site and Relic Society of Germantown. This Flora, with letterpress titlepage and running title contains news clippings of 35 articles written as a series, appearing every Friday from March 27 to December 11, 1903, in the Germantown Independent Gazette. Its 30 illustrations include portraits of 17 former residents.

Each article has an informal presentation of the author's wanderings about the fields, and reminiscences of his contacts in Germantown. Plants, both native and horticultural varieties are discussed as they appear in bloom during the season; each has a recapitulation of the species mentioned, both under the common names and scientific nomenclature. Nearly 500 persons, gardens, or industrial concerns are introduced in the ramblings and to these an index has been prepared.