Read. Read. Read.
When you are reading something (fiction, non-fiction, periodicals, blogs, instant messages from your friends, bulletin boards in public places, the menu in the café or restaurant), you are getting exposed to new words all the time. Sometimes, the meanings are guessable based on context. Sometimes, the meanings are guessable, based on context and root words. Sometimes, the meanings are not guessable at all based on context. You have to look the term up in the dictionary.
Pursue academic and intellectual hobbies.
Maybe you like reading about languages and linguistics. Maybe you like reading about theology and philosophy. Maybe you like reading about astrophysics. Whatever your academic interests are, you pursue them by reading peer-reviewed scholarly literature. If you go to university, then you may be assigned to read a lot of peer-reviewed scholarly literature. If you wish to do a research thesis, then you have to do a lot of reading and a lot of writing, and you have to speak the technical language so that other people will take you seriously.
If you go into chess club as a high school student, then you should expect chess-related terms. If you go into creative writing club as a high school student, then you should expect creative-writing-related terms. If you go into computer programming and software design, then you will be acquainted with lots of programming-related terms. And you learn them all contextually.
English can be a tricky language
One of the big trickiness of English is that there is really strong preference for making a whole different, seemingly unrelated word. Take your examples.
anther, corolla, pistils, sepal, calyx, stamen, filament, ovary,
ovule, peduncle, etc
How are they related? Look up the etymologies!
anther: early 18th century: from French anthère or modern Latin anthera, from Greek anthēra ‘flowery’, from anthos ‘flower’.
corolla: late 17th century (in the sense ‘little crown’): from Latin, diminutive of corona ‘wreath, crown, chaplet’.
pistils: early 18th century: from French pistile or Latin pistillum ‘pestle’.
In the Chinese language, the fact that the terms are all related to plants is pretty obvious. The 艹 part (grass radical) is telling.
Arguably, if you look up the etymologies in English or look up the meanings of Chinese characters, then they may actually help you remember the information. And of course, if you look at a flower diagram, you should label the flower diagram with flower anatomy terms. That way, you can remember the flower anatomy.
That's the easy part. If you take college anatomy class, then you'll have to remember a whole list of Latin words; and you may have to use mnemonics like "Oh, Oh, Oh, To Touch And Feel Virgin Girls Vagina And Hymen" for the cranial nerves.