IPA: //bəˈtæn.ɪ.zaɪər//
KK: /bɑːˈtæn.aɪ.zər/
A person who studies or collects plants, often as a hobby, and enjoys identifying different species in nature.
As a botanizer, she spent her weekends exploring the local forests to discover new plant species.
Botanizer is formed from "botan-" (from Greek "botanē", meaning plant or herb) and "-izer" (a suffix used to indicate a person or thing that performs a specified action). The word refers to a person who studies or collects plants.
Think of someone who studies 'plants' ('botan-') and is an 'actor' ('-izer') in that field — that's what a botanizer does.