Isobel Agnes Arbuthnot

Isobel Agnes Arbuthnot (1870–1963) was an Irish-born botanist and botanical collector based in South Africa.

Arbuthnot was born in Belfast in 1870 and went to Cape Colony in 1888 for her health where she took a position as companion to the wife of Harry Bolus. There she also worked as a botanical collector and the botanical assistant on Bolus's expeditions. From 1918 until 1939 she worked in the Bolus Herbarium before moving to the Compton Herbarium, located in the Kirstenbosch National Botanical Garden, before finally retiring in 1945.

She died in Newlands, Cape Provence, South Africa in 1963.

The plant Lampranthus arbuthnotiae, a succulent, is named after her.