Vittarioideae worthy of subgeneric rank, while "Rheopteris" had not yet been discovered. "Haplopteris" he explicitly synonymized with "Vittaria" in 1914. Carl Christensen used the name "Vittarioideae" in Verdoorn's "Manual of Pteridology" in 1938, but did not include a description, leaving it nomenclaturally invalid. Ren-Chang Ching raised Vittariaceae to the rank of a family in 1940. The first well-sampled molecular phylogenetic study of the vittarioids was based on the chloroplast gene rbcL. In this study, it was found that the type species of "Monogramma" is embedded in "Haplopteris"; the segregation of "Vaginularia" from "Monogramma" was also supported, as members of "Vaginularia" formed
Human uses of plants in genetic engineering led to developments in crops. Genetically modified crops introduce new traits to plants which they do not have naturally. These can bring benefits such as a decrease in the use of harmful pesticides, by building in qualities such as insect resistance and herbicide tolerance. The ability of trees to graft is occasionally exploited by tree shaping to create living root bridges in Meghalaya and Nagaland states in India and on the islands of Sumatra and Java in Indonesia. The aerial roots of rubber fig trees, "Ficus elastica", are used to form suspension bridges across mountain streams. Plants