I post many essays on the plants of our Kitsilano (Vancouver, BC) garden. My wife and Rosemary are sticklers in using correct botanical nomenclature. This is the botanical system introduceded by Carl Linneaus called binomial nomenclature.
As an example you have the trees of the Genus Magnolia. In a strict correctnes when you write about the plant it is in italics — Magnolia. The genus (like in all the other plants with few exceptions) has many species. Thus we have Magnolia virginiana.
The Southern Magnolia is Magnolia grandiflora. We have recently purchased a cultivar (a plant found in gardens but not in the wild or cultivated by experts who look for the best varieties of plants) called Magnolia grandiflora ‘Alta’. The name (not in italics) between single quotes signifies that this is a plant discovered in a garden and or grown or selected by cross polination by a human.
Alas! In this essay I wrote today https://medium.com/latin-american-literature/the-beetle-the-magnolia-1411aa1e968f I am unable to correctly identify the plant in the caption.