If you don't carry a ruler you can use a quarter which is an inch in diameter.
Although flowers may be easy to measure, the size often varies. Botanical descriptions often do not
include the flower size so some of our size information may be wrong.
When a plant has clusters of small flowers you should measure the size of
a flower even though it may be very small. Many plants have flowers that are not obvious and in
that case we put them in the "Very Small" category.