Contains some of the earliest attempts at printing copper plates in color. The plates were "engraved by [Elisha] Kirkall in what is generally called 'mezzotint printed in colour.' The phrase is misleading. ... Kirkall achieved a half-hearted imitation of true mezzotint by rather clumsily roughening the toned parts of the plate with a roulette and leaving the rest of it untouched. The so-called 'colour-printing' was equally elementary: many of the figures are merely printed in a mossy green and touched with water-colour; in a few of the others, two or three different coloured inks have been used in a single printing." (Wilfrid Blunt, The art of botanical illustration (1950), p. 133.)
"Historia Plantarum Rariorum depicted plants from the Chelsea Physic Garden and the Cambridge Botanic Garden. These plants had come from the Cape of Good Hope, North America, the West Indies, and Mexico. Elisha Kirkall produced the mezzotint engravings. Each plate was dedicated to a patron and showed an engraved coat-of-arms or monogram. Besides van Huysum, other artists were William Houstoun, Massey, G. Sartorys, and R. Sartorius. The work was published in five parts of ten plates each between 1728 and 1737, and was sold by subscription. The venture was not a financial success and publication ceased in 1737" (Wikipedia article on Jacob van Huysum, accessed 10-2021).
Digital facsimile from Biodiversity Heritage Library at this link.