Chrysanthemum

Here is a lovely botanical illustration for the next bloom on the white flower list - chrysanthemum.

Not all chrysanthemums have these large puffy blooms but when they do they are necessarily the main element of any arrangement that includes them.  With such striking beauty they don't really need any accompaniment other than a little greenery to make a stunning display.  If the arranger wishes to add some contrasting color, it could be other such mums or a similarly shaped bloom in a different color or perhaps some very compact flowers.

Image:  Botanical illustration from International Encyclopedia.  From Wikimedia Commons - in the public domain in the United States.