What is noun in English​

A noun is a word that names something, such as a person, place, thing, or idea. In a sentence, nouns can play the role of subject, direct object, indirect object, subject complement, object complement, appositive, or adjective.

covert: hidden or secret

candid: truthful and straightforward

what i get from these phrases is covert means undercover or underground and that's where the flower is in april. on the other hand, may is the month where flowers start to bloom and thats the reason why candid is being used as a word to describe the blossoming period of a flower.

hope this answer you.