In botany class, we became quite good at identyfying types of flowers. IS identyfying PP DO

Answer 1

I think the OP means to ask if "identifying" is a past participle or direct object. But I could be wrong...

Answer 2

The word is spelled "identifying" and it's a gerund serving as the object of the preposition "at" -- and "types" is the direct object of "identifying" and "of flowers" is a prepositional phrase modifying "types."

http://grammar.ccc.commnet.edu/grammar/verbs.htm#gerunds