Given the context and the title of the passage, plants sprouting is the most logical choice. When the passage says, "Rooted, they grip down and begin to awaken," you can come to the conclusion that the author is referring to plants since the passage is about spring.
Chimamanda Ngozi Adichie Commencement Speech to the American University... From my poetry and years before when I began writing stories as a kid in little notebooks. ... And spellings, which means the text messages don't count. ... When you've been immersed in reading here at the AU for the last few years.
