Hopefully this is the right idea!
A. If plant has no flowers go to B.
A1. If plant has petals go to C.
B. Plant has needles go to D.
B1. Plant has no needles go to D.
C. Plant has purple petals go to E.
C1. Plant has white petals go to E.
D If plant uses cone to reproduce (plant 1)
D1. If plant has many anthers (plant 4)
E.Plant has leaves on stem (plant 2)
E1.Plant has no leaves (plant 3)
Hi Carrie! I liked how your key was pretty easy to follow! You could make your key a little shorter by saying at B if it has needles it will be plant 1 , at C if it has purple petals it will be plant 3 , and at C1 if it has white petals it will be plant 2.