Maurice William Holtze, (8 July 1840 – 12 October 1923) born in Hanover, Germany, was a botanist who established Darwin's Botanical Gardens in Fannie Bay, Darwin in 1878. When he left to take charge of Adelaide's Botanic Garden in 1891, his son Nicholas was appointed curator of the Darwin Botanical Gardens in his place.
Holtze studied at Hildesheim and Osnabrück before serving an apprenticeship in Hanover, where he subsequently worked for four years in the Royal Gardens. He spent two years in the Imperial Gardens of St. Petersburg before emigrating in 1872 to Melbourne, then to Darwin, Northern Territory.
While in Darwin (then called Palmerston, later Port Darwin) he made trial plantings of a large number of tropical plants of potential economic importance: rubber, rice, peanuts, tobacco, sugar, coffee, indigo and maize. He supplied the sugarcane tubers for the Cox's (later Cox) Peninsula sugarcane venture in which B. C. DeLissa and W. H. and G. T. Bean had a large interest.
Holtze sent a large number of botanic specimens from the Darwin area and nearby islands, many of which had not been previously described, to Sir Ferdinand Mueller.
In Adelaide, succeeding the great Dr Schomburgk as curator, he did much to make the Botanic Gardens an attractive place for the general public to visit, a novel policy at the time. He established lakes populated with water-lilies and lotuses, which became quite famous.
He retired in 1917 and died at Kangaroo Island, South Australia in the home of his daughter. He is buried in Penneshaw Cemetery, Kangaroo Island, South Australia along with his wife, Evlampia (née Mizinzoff), who died 5 July 1937. A son, Alexis L. Holtze, was Horticultural correspondent for the Mount Barker Courier, and editor of the Garden and Field.