His son Louis was appointed landgrave of Thuringia in 1130 by the emperor Lothair II.; by his marriage with Hedwig of Gudensberg in 1137 he obtained a large part of Hesse.
He married his cousin Hedwig Elizabeth Charlotte of Holstein-Gottorp (1759-1818), but their only child, Carl Adolf, duke of Vermland, died in infancy (1798).
Soon after the promulgation of Linnaeus's method of classification, the attention of botanists was directed to the study of Cryptogamic plants, and the valuable work of Johann Hedwig (1730-1799) on the reproductive organs of mosses made its appearance in 1782.
By his beloved consort Ulrica Leonora of Denmark, from the shock of whose death in July 1693 he never recovered, he had seven children, of whom only three survived him, a son Charles, and two daughters, Hedwig Sophia, duchess of Holstein, and Ulrica Leonora, who ultimately succeeded her brother on the Swedish throne.