Thank you to Ruth for today's scan and write-up:
What may look like a typical Impatiens-type flower in this image is apparently very rare! This is a scanned image of a colour reproduction from Curtis's Botanical Magazine Vol 127, TAB: 7809. This 1901 publication is where Joseph Dalton Hooker first described the species in a publication (and copyright has expired on the original image). This reproduction does not express a true sense of the size of the species; for example, the flowers are around 5cm (2 in) in diameter.
The species does not closely resemble the typical nursery-grown impatiens in wide cultivation (i.e., hybrids of Impatiens walleriana) and sold as 6-packs for your shaded garden areas in need of some colour. Instead, Impatiens psittacina more closely resembles species like the tendency-to-be-invasive Impatiens glandulifera and reaches similar heights of 2m (6ft).
Impatiens psittacina, or the parrot-flower is from north Thailand, Burma and portions of east India.
Steve Lucas writes extensively about Impatiens psittacina on his web site, Exotic Rainforest in this article: The Rare Thailand Parrot-Flower. Steve also notes that the only public garden known to have an individual of this rare species (that he's been able to locate) is the Queen Siktri Botanical Garden in Chiang Mai of Thailand.