A genus (genera in the plural) is a group of plants or animals that not only share certain key characteristics with others in the Family but also display certain unique characteristics which help to group them together. Each genus is further separated into sub-groupings called species. So, a genus may consist of as few as one and as many as thousands of species.

The genus name is always capitalized and shown in italics when printed by machine or when handwritten, is should be underlined.

Mr. PGC Comment: There is really no big mystery why these words are italicized or underlined. The simple reason is that scientific names are not made of English words but rather, "Latinized" words. So, just like the French phrase, Parlez vous, or the German, Sprechen zie, the foreign words of scientific names of plants need to be printed in italics or underlined to make them stand out.

When referring to the genus name, it should appear as Hosta. This would be used in the phrase, "That plant belongs to the genus, Hosta."  However, since this is also the common name used for this group of plants, it may also appear just as hosta as in "There are several hosta plants in the garden".  Although I have seen some debate on the issue, the proper plural is hostas when used as a common name and not hosta. So, you would say, "I have several hostas in my garden." not "I have several hosta in my garden." Confusing? Sorry.

Mr. PGC Comment: Do you realize that this genus was once called Funkia? After its introduction from Asia to Europe a couple of hundred years ago, the plant was thought to have been named after a guy named Heinrich Christian Funck (1771–1839). Fortunately, at least in my opinion, it was later determined that the genus had first been named after Nicholas Host (1761-1834), an Austrian botanist resulting in the genus name, Hosta. Since this name showed up first in the literature, it took precedence.

Liberty Hyde Bailey's Cyclopedia of American Horticulture in 1919 listed Hosta as the proper genus name with Funkia being an out of date alternative. Unfortunately, in the 21st century, you will still see the name Funkia used in some books, articles and even on plant name tags occasionally.