Scientific names consist of two words, the genus and the species epithet (think of the second word as the describer). Many unrelated plants can share the same species epithet (description, ie. macrophylla which means big-leaved) but only plants very closely related to each other share the genus. Both the genus and species epithet should be written in italics. The genus should be capitalized and the species epithet is written in all lowercase. Specific populations of plants will have further designations. For example: forma (abbreviated f.), variety (var. or v.), cultivar (which stands for cultivated variety). The cultivar name should not be italicized, but it is capitalized and in single quotes. So an example of appropriate punctuation would be:
Welcome! I’m Margaret Roach, a leading garden writer for 25 years—at ‘Martha Stewart Living,’ ‘Newsday,’ and in three books. I host a public-radio podcast; I also lecture, plus hold tours at my 2.3-acre Hudson Valley (NY) Zone 5B garden, and always say no to chemicals and yes to great plants.