What is a plant? There are many deeply strange forms of life on earth that do not conform to our three kingdoms model of the world. What counts as a plant, and what doesn’t? This is the first of a new series of posts that will look under the hood of some everyday plant concepts. We’ll start at the very beginning, asking “what is a plant?” Send me any of your plant quandries and I’ll try to answer them. (Cover image of diatoms--are diatoms plants? Photo by Zeiss Microscopy CC license)