Final answer:
The species part of the name Pisum sativum 'Early perfection' is Pisum sativum. The name 'Early perfection' refers to the cultivar, a variety selectively bred for specific traits.
Step-by-step explanation:
The species part of the name Pisum sativum 'Early perfection' is Pisum sativum. In the taxonomic hierarchy, the species is the basic unit of biological classification and is indicated by the first two parts of the scientific name, where the first part is the genus (Pisum) and the second part is the specific epithet (sativum). The name 'Early perfection' that follows the species name is the cultivar, which is a variety of the pea plant that has been selectively bred for specific characteristics, in this case, likely its early maturing nature. The term 'perfection' in 'Early perfection' denotes the distinctive qualities of this particular cultivar.