Accurate records of the origin of the Boston fern (Nephrolepis exaltata bostoniensis) and its many varieties compose one of the most complete histories of any cultivated plant. The Boston fern mutation was discovered among 200 Sword ferns by a florist near Boston in 1895. The Sword fern (Nephrolepis exaltata) is native in Florida and throughout the American tropics. This wild species was introduced at Kew in 1793 from Jamaica. For 100 years it remained stable, and by 1895 it was used widely as a house plant. The Boston fern was more desirable as a house plant, and gradually replaced the wild species almost entirely. Benedict (1916) estimated that from 1,000,000 to 2,000,000 Boston fern plants are propagated each year in the United States., Plants from the southern states, and from the western, northern, or central part of the country, could not be distinguished from those of eastern Massachusetts. However, six exceptions to this statement must be nioted. Within a few years of each other there appeared in the greenhouses of commercial growers in five states, amid countless thousands of normal Boston ferns, six mutations now known as Scott's fern (Scotti), Giatra's fern (Giatrasi), Pierson's fern (Piersoni), Foster's fern (Fosteri), Harris' fern (Harrisi), and the Roosevelt fern (Rooseveltti). From these six mutants numerous other varieties have been derived, many of which have not been named. Within the 45 years since the Boston fern appeared, over 200 varieties have come into existence, many gaining commercial importance. Some of the noteworthy facts concerning these numerous mutants are as follows: 1. From what was originally a stable species a mutant (Boston fern) was discovered among thousands of Sword fern plants after the species had been cultivated for about 100 years. 2. The wild species (Nephrolepis exaltata) produces fertile spores, but the Boston fern and all of the derived varieties are sterile, except one (Nephrolepis exaltata bostoniensis f ertilis). Fertilis was a mutant from Piersoni. 3. The Boston fern is of such a xerophytic type that it can withstand the dry atmosphere of the average home-which is drier than desert air. The other extreme is reached in a form which must be kept in a saturated atmosphere to keep it alive. 4. One variety, elegantissima-compacta 1 Papers from the Department of Botany, The Ohio State University, No. 425.