Q. How to Prepare a Key?

Let us prepare a key by making a choice of. characters, listing significant and insignificant characters, tabulating these characters and forming dichotomies. List all the permanent morphological characters and write them in the same sequence on cards. Keep one card for each taxon. If we choose petiole as a character we have to write it at the same number in all the cards. 

From the table it. is clear that taxa I, I1 and I11 fall into one group and IV in another. On the basis of characters noted at 1,2 and 3. This is called Dichotomy. On the basis, of perianth character written at No. 4 again two groups are made, one of taxa I. and. I1 and other of taxa I11 and IV. Taxa I and I1 are further separated on the basis of character of petals, free versus connate. Now sort out all the cards into two groups and separate cards of each group into two or more sub groups till all the taxa are dealt with and all the cards are sorted out. All the characters on the basis of which cards are sorted into groups form the couplets of leads. Now print the key and write flower trirnerous and not trimerous flowers and leaves reticulate and not reticulate leaves. f size is a character then give range of measurements and do not use words like big, small large.