This is a genuine image of a cross section of grass leaf under a microscope. No part of the leaf is "smiling" in any literal sense, of course, but the round features known as "vascular bundles" do resemble "smiley faces" when viewed from above.
An image that appears to show a bunch of little “smiley faces” peering out at the viewer from under a microscope has been circulating on the internet for years.
In a meme that has been shared by social media users since May 2021, the image is accompanied by a caption that reads, “This is what a blade of grass looks like under a microscope. Next time you take a walk outside, know that the grass is happy to see you.”
A discussion about the image cropped up in 2015 on the question-and-answer site StackExchange, where a user with an anonymous profile pointed to a similar image on a science stock photo website that was captioned:
Marram grass leaf. Light micrograph of a cross section through a closed (unravelled) leaf of Marram grass, Ammophila arenaria. The deeply grooved leaf is thrown into folds (seen here) and it uncurls when mature so that the folds do not face the centre. The folds conserve water and withstand salt, and prevent excessive evaporation. Round vascular bundles are visible inside each fold, serving to transport food and water through the leaf. Spines on the surface discourage animals from eating the leaf. Marram grass is important in coastal ecology, since it is one of the commonest grass species in Britain to stabilize sand dunes. Magnification: x22 at 35mm size.
Maria Morrow, assistant professor of botany and environmental science at College of the Redwoods, pointed out that the “smiley faces” are in fact vascular bundles typical in plants called monocots — plants that are only composed of one leaf, like grass.
So although the above image does depict the components of a real leaf cross section under a microscope, it’s safe to say that the image doesn’t in any literal sense show a leaf “smiling” or “happy to see you.” In fact, describing these characteristics as smiley faces is a subjective call. Looking at the image included in Morrow’s article, one could argue the leaf is actually screaming at you:
In other words, the “smiley faces” are just an illusion created by viewing a slice of the leaf’s round vascular bundles from above, through a microscope lens.