Here's why:

* Earth is a planet: It's a massive celestial body, not a plant.

* Plants come in all sizes: From microscopic algae to giant redwood trees, plants exhibit a huge range of sizes.

So, it's impossible to say which plants are smaller than "Earth" because Earth isn't a plant!

Perhaps you meant to ask:

* What plants are smaller than a certain size? For example, "What plants are smaller than a basketball?"

* What are the smallest plants? This would involve looking at microscopic organisms like algae.

Please clarify your question so I can give you a more accurate answer. 😊