Corn germination. The other two stems are intruders and are most likely grass stems. You can see the distinct difference in the two grass blades and the corn stalk. The corn stalk is much more firm and sturdy compared to the two other stems showing the ability to produce vegetation. 

Bean intruders. They are dicot stems but there a many identical stems and they appeared in the previous failed plant environments therefore none of these are the bean's stem.