We are all familiar with maple trees and their majesty. We know their regal fiery orange autumnal colors and the rich (in more ways than one) maple syrup their sap produces. But who could forget about their–acorns!? Not so much. Maple trees do not produce acorns. Instead, they produce samaras, which you might know by the more commonly-used name “helicopters.” Both acorns and samaras are similar in that they are the seeds of the tree, but acorns are the seeds of oak trees whereas samaras are the seeds of maple trees. These two seed types represent two distinctly different reproductive strategies between oaks and maples, and it is important to understand the difference. That said, acorns and samaras do share an important commonality. Let’s dig into that first.
The Similarity Between Acorns and Samaras
Of course, acorns and samaras are both tree seeds, but beyond that, they share one important commonality. Trees are divided among two groups: Angiosperms and gymnosperms. The difference between the two is that gymnosperms produce “naked” or unprotected seeds while angiosperms produce seeds protected by a fruit. Both acorns and samaras are produced by angiosperm trees, and so acorns and samaras are thus both protected by a pericarp that surrounds the seed and contains energy stores for the germinant. but that it where the similarities end. Beyond their basic biology, acorns and samaras are distinctly different seeds with different regenerative strategies.
Only Oak Trees Produce Acorns
The key characteristic of acorns is that acorns are only produced by oak trees. No maple tree will ever produce acorns, as they are specifically the seeds of trees within the Quercus genus, which is the genus of oak trees. Within the genus of Quercus, however, are over 500 unique oak species, so while acorns are only produced by oak trees, they are still produced by a great diversity of species!
Not all acorns are alike either. Each species of acorns produces a different acorn with unique characteristics. Red oak, white oak, and chestnut oak, for example, can all be uniquely identified by their acorns. You can learn more about acorn identification here.
All Maple Trees Produce Samaras
Just as all oak trees produce acorns, all maple trees produce samaras. As mentioned previously, samaras are the seeds of a maple trees and contain the same parts of an angiosperm seed as an acorn, but instead of being encased in a hard shell that falls straight down, samaras (often called “helicopters”) slowly descend downward being carried by a single wing that rotates and floats in the wind.
While maple samaras don’t have quite the same level of physical differences observed in acorns, they still have distinct characteristics that can be used to differentiate the species of maple a given samara comes from. You can find a useful guide here.
Samaras Are Produced by Many Other Trees Besides Maples
Acorns are unique to the Quercus (oak) genus, but samaras are produced by a variety of genera, including species of ash and hornbeam. However, maples are the only genus that produces the quintessential scimitar-shaped samaras that most are familiar with. Ash trees, for example, produce symmetrical elongated tear-shaped samaras, as seen below. Though the shape differs, the function is entirely similar: The “wing” helps the seed to travel further with the wind.
The Evolutionary Strategy of Acorns and Samaras
The characteristics of acorns and samaras represent two distinct evolutionary strategies that oaks and maples have taken over the course of millennia.
Trees all have a fundamental problem when it comes to reproduction and regeneration: If a seed germinates below the parent tree, the shade of the parent will limit the growth of the seedling and maybe even kill it entirely. Thus, trees have evolved strategies to carry seeds from out from the shade of the parent.
In this context, the function of the samara is obvious. The “helicopter” function of the wings help the seeds travel a fair distant, hopefully landing and germinating outside of the shade of larger trees. The function of an acorn is less obvious. Acorns are large and heavy, and they tend to drop straight down. That’s where wildlife comes in.
Acorns are big and meaty, containing vital nutrients like fats and proteins that are indispensable for wildlife. When oak trees drop their acorns, it is an all-you-can-eat buffet for the animals. You might think that is a bad thing for a tree hoping to give the best chance for its seeds to germinate, but it’s a tradeoff. As animals feast on acorns, the seeds are carried far and wide by squirrels and birds that inevitably drop them or lose a certain percentage of them. Thanks to these critters, a single oak tree can spread seed for miles, despite having heavy seeds that cannot be carried by the wind.
Understanding Seeds is Key to Understanding Forests
While the seeds of a tree may seem to be a detail that is small and insignificant, seeds, their function, and their characteristics can tell us an awful lot about trees and how they survive and thrive in given environments. Whether trees such as maples produce acorns or samaras can give us clues to the ecology around us. Whether you are a timberland owner looking to learn more about your forest or a curious lover of the outdoors, hopefully this article helped you appreciate acorns and samaras and their respective functions a bit more.