After spending from September, 1911 until July, 1914, in that position, he returned to the United States and in the fall of 1914 began graduate studies in botany at Columbia.
He took a position as Research Associate (1960–1981) at the University of Michigan Herbarium[2] with over 30,000 plant specimens that he had collected in India, Kashmir, Iran, etc.
In recognition of his services to educational and botanical work, Stewart was awarded the Kaisar-i-Hind Medal in 1938, and the Sitara-e-Imtiaz (Star of Distinction) in 1961.
In 1972, botanist Eugene Nasir published Stewartiella is a genus of flowering plants from Afghanistan and Pakistan, belonging to the family Apiaceae and was named in Ralph Randles Stewart's honor.
The Stewart Collection has been deposited in the National Herbarium of the government of Pakistan at Islamabad, leaving a very rich heritage for the students of plant sciences.
Stewart returned to Pakistan in 1990 to visit Gordon College and make a presentation at the International Symposium on Plant life of South Asia.
Two of us worked in Gordon College, Rawalpindi, at the beginning of the cart road to Kashmir constructed in 1890 with a good deal of cost and difficulty.
Instead of returning to Kashmir we turned east from Leh, crossed the Rupshu plains and entered Lahul by the Baralacha Pass; left Lahul by the Rotang La, visited Kulu and then walked further east to Simla and returned home from there by train.In September 1916, Stewart married Isabelle Caroline Darrow (1888-1953) at the bride's home in Middlebury, Vermont.
The couple met studying for graduate degrees in science at Columbia in 1915, both wishing to return to teaching abroad.