In the Sonoran Desert we have “nursemaid plants,” but up here in Yellowstone National Park we have “nursemaid rocks”!
This is a photo of a Douglas fir tree (actually an evergreen conifer species in the pine family) growing out from under a huge boulder. Well, it’s actually the roots of the tree that are under the boulder. These are glacial erratics (left on the landscape when glaciers receded) and there are lots of them in the Northern Range of Yellowstone. In this area the Douglas fir trees are on the edge of their ability to reproduce and the erratics provide enough of an environmental modification for them to grow. These erratics provide a young seedling with shade, moisture, shelter from wind, and they absorb and radiate heat which melts the surrounding snow faster. Douglas fir seedlings prefer to grow initially in shade and if a seed which is carried by the wind falls near a protective rock, it has a better chance of germination than if it were out in the open, more harsh environment.
Similarly, in the Sonoran Desert the nursemaid plants protect our young saguaro seedlings.