"Polygonaceae is mainly a north temperate order. A few genera are tropical which has 125 species restricted to tropical and sub—tropical America. Polygonum has a very wide distribution to the mountains of tropical Africa and South Africa, through the highlands of tropical Asia to Australia, and in America as far south as Chile. Most of the genera have a limited distribution. Of the three which are native in the British Isles." —Encyclopaedia Britannica Company, 1910

Flowers and Leaves of Common Dock

"Polygonaceae is mainly a north temperate order. A few genera are tropical which has 125 species restricted…