After being transferred to Middelburg in the Cape, he developed an interest in the local plants and spent long hours dissecting and identifying wild flowers with the aid of the three volumes of Flora Capensis and Harvey's Genera.

His specimens now started reflecting his meticulous nature in that they were carefully pressed, preserved and labelled with extensive notes on locality, habitat and plant form.

His duplicates soon found their way to Kew, Zurich and a number of notable botanists such as Harry Bolus, John Medley Wood and Peter MacOwan.

In Barberton he befriended a young lawyer and plant collector Douglas Gilfillan, later to become his brother-in-law through their marriage to the de Jongh sisters.

Galpin had had some new plant discoveries painted by Marie Elizabeth de Jongh (the daughter of Countess Mimi von Schönnberg) and married her in 1892.

He made extensive collecting trips to mountains in the Eastern Cape, including Great Winterberg, Katberg, Stormberg and Andriesberg.

In 1897 he set out on a trip from Port Elizabeth to Humansdorp, Knysna, George, Riversdale, Swellendam and Caledon districts, ending in Cape Town.

In 1907, in the company of Prof. HHW Pearson, he undertook a trip to South West Africa to study Welwitschia, making stops at Port Nolloth, Lüderitz Bay, Swakopmund, Welwitsch Station and following the Swakop River to Haikamkab.