You also communicate with others (not-you). You know that there are others because you can gain knowledge from them, which you didn't have before. And in that knowledge lies awareness of your self and consciousness.
Elm definitely have heart to hearts with each other. If we watch them on a long-enough timeline, they definitely set and achieve goals (for themselves and others).
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In my previous book recommendation (Pollan) there is a chapter on plants observed in timelapse/FFW, which have been able to effectively "remember solved mazes" (not exactly, but neat studies/equivalents) – similar to slime molds (as described in Entangled Life [1]).
Books don't work for things like this. Where are the papers? Start with actual science, exhaust all avenues on that and then the philosophy can be approached.
Each of the above-linked books is filled with citations, including dozens of other researchers' papers. Start with general philosophy, exhaust all avenues on that and then the "scientific" can be approached.
Perhaps you can share some of the more relevant links so there many of us who aren't interested in buying entire books can check them out. Unless your purpose here is to promote said books, in which case I wish you luck.
It really doesn't make sense to start with philosophy as there's little to no grounding data, and philosophy is vast; essentially limitless. Science is required as grounding so the study has a foundation and discussions can be properly scoped.
Is an elm also conscious?