If asked to describe a plant, many of us would have to resort to basic descriptors such as vague shapes or simple colors. But for those who work and write in the plant world, there are thousands of terms available for crafting the perfect characterization. A pear's shape can be called pyriform, while lemon's form is prolate. A petal might range from caesious (pale blue-grey or -green) to ceraceous (pale cream) to cinerous (ash grey). And the autumnal spread of fallen leaves is called, elegantly, leaf litter.

The Kew Plant Glossary is a...