What are the singular subject pronouns in phrase a cactus blooms desert.?

Let's break down the phrase and find the singular subject pronouns:

* "A cactus blooms desert" is grammatically incorrect. It should be "A cactus blooms in the desert."

* "A cactus" is the subject of the sentence. It is a singular noun phrase.

* Subject pronouns replace nouns in a sentence. The singular subject pronoun that could replace "a cactus" is "it".

Therefore, the singular subject pronoun in the phrase "A cactus blooms in the desert" is "it."