The angiosperms or true flowering plants are presently the most dominant plants on Earth, comprising more than 95% of all existing plants (embryophytes or land plants).
They also represent most of the agricultural and food crops (Kesseler and Stuppy 2009; Simpson 2010).
It is just proper therefore that this group of plants is accorded special concern.
These plants consist largely of monocotyledons and eudicots.
Combined, they comprise 246,000 described species, equivalent to 97% of all angiosperms as of 2010 (Simpson 2010).
Mathematical derivation indicates that there are more than 250,000 species of angiosperms.
These flowering plants exhibit wide diversity.
They occur in various sizes, forms, growth habits, life spans, and habitat preferences.
Their sizes range from less than 1 mm in diameter, as in the smallest flowering plant Wolffia, to more than 90 meters or 300 feet in height as in the eucalyptus trees of Australia.
Wolffia is a water surface dweller and produces the smallest flowers.
Although orchids may not appear so extraordinary, they produce seeds that can be less than 0.2 mm wide (waynesword.palomar.edu 2012), the smallest seeds.