I can't make what I want to happen, happen.

I have attached the spreadsheet I am working on called Tree Sample Form. In this Excel spreadsheet, I have three worksheets. One is called "Tree Data"; the second, "Bark_Cone_Leaves"; and finally "Summary".
In the "Tree Data" worksheet I want to mark off which species I have in a sample. Then on the "Summary" I want the descriptions of cone, bark, and leaves to appear beside the species.
I can make all of this happen, but on the "Summary" worksheet, any species I have not marked off in the "Tree Data" shows up as "#N/A". I don't want this. In fact I want no space between the different species in a sample.
Please look at my attached example and HELP!!!