Question about taxonomy

I've wondered for the longest time, and this seems the best place to ask the question.
I only took a year of Latin, but is "speciosa" really just a nice way of saying "some sort of"? In other words, does Catalpa speciosa just mean "some sort of catalpa", but no one's worked out the details?

 

According to Stearn's "Botanical Latin'', speciosus is an adjective meaning "showy, splendid", but speciosa wasn't found in the book.

 

That's just gender - speciosa is the feminine form of speciosus.

 

Thanks Michael, thought the meanings might be similar, but hadn't thought of gender.