William (Leonhard Carl Wilhelm) Bauerlen was a German born botanical collector who collected Australian plants for Baron Ferdinand von Mueller for several years and was employed as a botanical collector by Joseph Maiden at the Technological Museum, Sydney, from 1886-1904. Bauerlen was a friend of Kenneth McKenzie (1836-1922), the youngest of six children of Thomas and Mary McKenzie, Scottish emigrants to the Shoalhaven district on the south coast of New South Wales in 1839. Bauerlen and McKenzie probably first met in 1886 when Bauerlen began collecting botanical specimens around Cambewarra, where the McKenzie family lived at a property called Fairfield. In 1886 Kenneth McKenzie was responsible for the design and building of Meroogal in Nowra for his widowed older sister Jessie Catherine Thorburn (1824-1916).
Bauerlen's name appears in the diaries kept by Tottie/Tot Thorburn, Jessie's daughter and Kenneth McKenzie's niece. Tot records a visit by Bauerlen to Fairfield in April 1888 when he and Kenneth spent two days on the mountain collecting specimens. There were further visits in May and September 1888 and again in November 1890.The surviving book collection from Meroogal includes a copy of Bauerlen's
The wild flowers of New South Wales by William Bauerlen and Gertrude Lovegrove, Sydney, Angus & Robertson, 1891.