The paper referred to here was Scott's on Oncidium.
"More Letters of Charles Darwin Volume II" by Charles Darwin
Among the special merits of the Oncidium is its colour.
"About Orchids" by Frederick Boyle
This admirable collector was hunting for Oncidium splendidum, a stately flower not very uncommon once, but long extinct in Europe.
"The Woodlands Orchids" by Frederick Boyle