Hello, Mrs. Rorick.

You're right; it seems to be a typo or perhaps an ideogram who didn't scan properly.

That word resembles 葉鞘, which is a botanical term.

There're more botanical terms such as 葉身 and 葉脈 that can have the suffix 部 attached to them.

Then we have botanical terms like 葉鞘部, 葉身部 & 葉脈部

According to デジタル大辞泉, each one means a specific part of a leaf.

We can see 葉稍 near botanical terms across the internet, as in a found paper:

葉稍部、葉身部ともに柔らかく、食味が優れると評価されている。

The word 葉稍 doesn't exist; it's probably a common typo or mistake.

In addition, the meaning of the term 葉鞘 as a botanical term seems to fit the context.