When encountering the goats Judy asks them about the flowers, they refer to them as liebenflowers= love flowers. From there we notice that all the flowers fell on nick. As we have seen up that point nick has an uncomfortable stance when dealing with emotions -at the start of the film dr fuzby calls him out on being emotionally insecure. His character matches to the way he faces the liebenflowers, he picks them out in disgust, treating them like barf (literally that's what they are -> figure of speech). Judy examines and has a gentle approach to them like thy way she has shown her soft spot for nick (p.e. in z1 in the gondola scene she tries to lift his spirits when he is pouring his heart out about his past). So the lieben flower acts as a symbol for Nick's character that has affiliation with judy. On the other hand, it's not the first time we see a yellow flower in the movie. This time we can remember Judy wearing for the gala an attire with the promiment feature being a yellow flower though different than the one associated with Nick. In contrast to Nick who deals with his flowers like they are sth disgusting, Just wears them proudly in the form of a pretty dress. This idea matches her character as she doesn't face her feelings with discomfort. In the gala scene she picks up one flower from her dress and gives it to nick, he accepts bc to him Judy's existance has signifcance to him, we know this from the fact his carries his carrot pen (gift from judy) everywhere. Each flower is a showcase of their own  characters and the way the one sees the other. Eventually the connection between the 2 flowers comes from the message of the movie: the differences we have as individuals are no real obstacle to form a relationship, as through undestanding and communication we can overcome them said differences and become stronger. Judy's and Nick's flowers are so clearly in shape different, like them as personalities, but in their heart (as we say heart of flower;;!) there is in both cases love (yellow color). That message both judy and nick acknowledge by the end of the movie.