Background
She was born in Battersea, Surrey, England on 27 May 1832. Hetley was the second daughter of Annette and Dugald McKellar, a doctor. The family moved to Madeira when Hetley was around 10 years old as a result of the poor health of her father.
Career
The family stayed on Madeira for the next 10 years but upon Dugald McKellar"s death, emigrated to New Zealand. The McKellars left in August 1852 and sailed on the Street Michael, arriving at New Plymouth on the December 2nd. They bought a block of about fifty acres of land at Omata, six miles south of New Plymouth, calling their farm Fernlea.
Hetley subsequently married a fellow settler Charles Hetly in the Omata church on 2 June 1856 and moved to Brookwood farm.
Just prior to their first wedding anniversary Charles died, leaving Hetly with a newborn son. When hostilities broke out in Taranaki in March 1860 Hetley moved to New Plymouth.
During her time in Taranaki, Hetley made pencil sketches of Fernlea and Brookwood, and of New Plymouth during the hostilities. She also painted watercolours of scenes in Waikato and Auckland.
Following a lecture about a botanical trip to Nelson, given by Thomas Frederic Cheeseman at the Auckland Museum in 1881, and with considerable encouragement from him, Hetley was inspired to attempt to do for the flora of New Zealand what Doctor Walter Buller did for its birds.
By 1884, she had started work on a book of native plants, The Native Flowers of New Zealand Illustrated in Colours, embarking (with the backing from the government and the Union Steamship Company) on a trip around New Zealand to obtain live specimens. Hetley went to England to seek a publisher, receiving assistance along the way from authorities at Kew, and the chromolithographers were ultimately produced in 1888 by Leighton Brothers. The plates also had the distinction of being published in a French edition a year later.
The inclusion in the book of Loranthus adamsii is notable as this native mistletoe was discovered by Mr James Adams of the Thames goldfields shortly before it became extinct.
Without the work of botanical artists such as Hetley there would be no record of what this plant truly looked like. Hetley returned to New Zealand in 1889 and exhibited her New Zealand flora at the General Assembly Library in Wellington.
She also help another major exhibit, 150 paintings in all, at Auckland Museum. Hetley lived in Auckland for the rest of her life, dying there after a long illness, on 29 August 1898.