Cleaning up 

Here's what I'm about to do to clean up this messy page.
First of all, sporange does not rhyme with orange, as clearly stated in the usage note. I will be moving it into the list.
Secondly, the section regarding orange, purple, silver, and month will be retitled "Words with obscure perfect rhymes".
Thirdly, the terms bulb, eighth, elbow, and of will be removed. Here is my justification:
No matter how obscure the rhyme, if it has a perfect rhyme, it must not be one the list. Bulb rhymes with culb, so it will be removed. Simple as that.
Eighth is a perfect rhyme for weighth, an alternative spelling and pronunciation of weight- compare heighth.
Elbow rhymes with beelbow, as was pointed out above.
"Of" rhymes with love in American English and "sov" (just look it up, yes, it seriously is a real word) as well as "thereof" in British English.