When we think of trees, some of the first images that spring to mind are those of the magnificent pines, cedars, and firs! Yet, these magnificent trees aren’t exactly what they seem. These trees are gymnosperms , and belong to a larger group of seed-bearing plants that do not produce fruits or flowers to protect their seeds. Rather, their seeds aren’t protected by anything at all!
Gymnosperms produce “naked seeds.” This means that their seeds aren’t covered by or enclosed in any structure. Yet, these seeds still have to be made. So, if these seeds don’t come from flowers, what structure makes seeds in gymnosperms? Let’s find out.
All gymnosperms today can be grouped into one of four classes . These groups are:
• Coniferophyta (Conifers)
• Cycadophyta (Cycads)
• Ginkgophyta (The ginkgo tree)
• Gnetophyta (Gnetum, Welwitschia, and Ephedra)
Conifers are the most abundant of these. Think Christmas trees, pine trees, and cedar trees. All of these are popular examples of conifers. Conifers, like all gymnosperms, don’t produce flowers. Conifers are defined by their production of cones. Cones are triangular or cylindrical woody structures that produce seeds in conifers. The most famous of these are pine cones, and for good reason.
Chances are, if you’ve ever walked through a temperate forest, you have come across hundreds of pine cones. You’ll see them scattered all over the forest floors. Pine trees, specifically red pine or Pinus resinosa, are the most common conifer in the world and can be found worldwide. Originally from North America, red pines can be found as far as Europe and Asia now.
Red pines have a very characteristic type of cone; they’re a little smaller and narrower than other pinecones and have a reddish-brown tinge to them (hence their name). Another important point to note about red pine cones is that the individual scales of the cone aren’t arranged in rows, but rather have a spiral arrangement to them. They also have smaller seeds than other varieties of pine.
Similarly, each variety or subspecies of pine has its own type of pine cone.
1. Mountain Pine: Mountain pines have cones that are much smaller than average cones. They only grow up to 5 cm long. An interesting fact about mountain pines is that when they first develop, they emerge a purple color. It is only when they mature that these pine cones turn to their characteristic brown color!
2. Ponderosa Pine: If mountain pines claim their place as one of the smallest pine cones, the Ponderosa pines proudly occupy the other end of that spectrum. The Ponderosa pines produce enormous pinecones.
They can grow up to around 20 cm in length. For scale, that’s the same length as a brick. The Ponderosa pinecones aren’t just large, they’re incredibly hard and woody as well. They have thick and durable scales that often terminate in a barbed point.
3. Virginia Pine: Aptly named, the species first identified in the eastern state of Virginia has a wide natural range. From Maine to Texas, this variety of pine can be found all along the eastern regions of the United States.
Virginia pines produce relatively small cones that can grow anywhere between 4 to 8 centimeters long. These cones diverge from the namesake “cone” shape and are rather ovoid or egg-like in terms of shape. They have a wide base that terminates into a point at its tip. If you can’t identify the cone by its shape, you can always go by weight, as Virginia pines produce surprisingly light cones. They also deviate from the general plan of producing distinct rows of scales and instead have their scales arranged spirally, similar to red pine cones.
4. Longleaf Pine: Longleaf pines are scattered all over the southeast regions of the United States. From the Carolina states to Florida, they are found in nine of the 50 states. Longleaf pinecones are massive and grow to be 10 cm long. They have thick and sharp scales that end in spines.
5. Jack Pine: Jack pines definitely produce some of the most unusual-looking cones of all the conifers. For starters, similar to mountain pines, jack pines produce an odd yellow or cream-colored immature cone that then matures into a brown cone. Weirder still is how these cones hang off the branches of the tree. Rather than hang off the branch, jack pines don’t produce cones in isolation. Rather, towards the top end of the tree, cones aggregate in clusters of two or more and angle forwards, along the branch.
They’re also highly specialized. They don’t release seeds unless exposed to extremely high temperatures, like those caused by forest fires. The fire literally melts the hard scales of the cones and only then do the seeds emerge from the cones to fall to the forest floors. This makes them super successful in areas more prone to forest fires.
6. Sugar Pine: Finally, we’ve saved the best for the last. Don’t be fooled by the cute name; sugar pines produce the biggest and longest cones of any of the pine species. They produce cones that can grow up to 60 cm long. That’s almost the length of a yoga mat!
Named for the sweet and fragrant resin they produce, almost every part of the conifer has value to humans. Early European settlers valued the tree for timber, while the Native American population used the seeds produced by the cones. The Native Americans collected the seeds and ground them into flour to make nutritious cakes that they then stored for the harsh winters.
Readability: 64.4
Flesch Kincaid Grade Level: 7.3
Glossary
Gymnosperms: Plants that produce seeds without flowers or fruit.
Scales: Individual units of a cone. Each scale is attached to a central axis and first contains ovules, as opposed to seeds. These ovules then develop into seeds once fertilized.
Class: A rank of biological organization of living organisms, more specific than kingdom but broader than order and family.
References
Types of Pine Cones: Large, Small, Giant, and More (with Pictures) – Identification Guide – Leafy Place. (n.d.). https://leafyplace.com/pine-cones/
The Secret Life of Pine Cones – Ypsilanti District Library. (2020, December 11). Ypsilanti District Library. https://www.ypsilibrary.org/2020/12/pine-cones/
Do Gymnosperms Produce Flowers & Fruit? (2021, September 30). Sciencing. https://sciencing.com/do-gymnosperms-produce-flowers-fruit-13428148.html
32.2: Plant Reproductive Development and Structure – Sexual Reproduction in Gymnosperms. (2018, July 16). Biology LibreTexts. https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Book%3A_General_Biology_(Boundless)/32%3A_Plant_Reproductive_Development_and_Structure/32.02%3A_Plant_Reproductive_Development_and_Structure_-_Sexual_Reproduction_in_Gymnosperms
Pinus ponderosa (ponderosa pine) description – The Gymnosperm Database. (2023, February 26). Pinus Ponderosa (Ponderosa Pine) Description – the Gymnosperm Database. https://www.conifers.org/pi/Pinus_ponderosa.php
Sugar Pine (U.S. National Park Service). (n.d.). Sugar Pine (U.S. National Park Service). https://www.nps.gov/articles/000/sugar-pine.htm
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