In pragmatics, exophora is reference to something extratextual, i.e. not in the immediate text, and contrasts with endophora.
Exophora can be deictic, in which special words or grammatical markings are used to make reference to something in the context of the utterance or speaker.
", it is quite possible that "those" refers back to the preceding text, to some earlier mention of those particular plants in the discussion.
But it is also possible that it refers to the environment in which the dialogue is taking place—to the "context of situation", as it is called—where the plants in question are present and can be pointed to if necessary.
A type of exophora, homophora relates to a generic phrase that obtains a specific meaning through knowledge of its context; a specific example of homophora can variably be a "homophor" or a "homophoric reference".