Final answer:
Exact numbers of plants and animals documented by Lewis during the expedition are not provided, but it is known that hundreds of specimens were collected and recorded.
Step-by-step explanation:
During the Lewis and Clark Expedition, hundreds of plants and animal specimens were documented.
Unfortunately, there isn't an exact number given in the provided information as to how many plants and animals Meriwether Lewis wrote about in his journal.
However, it is known that the expedition collected and recorded a substantial number of specimens, with several being named after Lewis and Clark in recognition of their efforts.