File:Acer platanoides seeds.jpg - Wikimedia Commons
Gurney's - America's Most Complete Seed and Nursery
Gurney's - America's Most Complete Seed and Nursery
Gurney's - America's Most Complete Seed and Nursery
Tillinghast Seed Company Historical Information
Big Business: Gregory, James J. H.'s Seed Catalog an AAS Online Exhibition
File:Starr 070221-4867 Guaiacum officinale.jpg - Wikimedia Commons
A schematic drawing of a typical cotton seed at maturity.
File:Tillinghast Seed Co. materials (Page 16) BHL48171087.jpg - Wikimedia Commons
Plantwise Knowledge Bank