What do we know about pine cones?

Various pine cone designs (Dyck Arboretum, Hesston College)

Pine cones are the seed-bearing organs of conifers and cycads (trees with cones and needle-like or scale-like leaves that are typically evergreen). Conifers are members of the group of plants called gymnosperms, and in addition to having cones and needles, they do not have flowers but their seeds are "naked". That means they are exposed on the cones instead of being protected inside an ovary or fruit like angiosperms (flowering plants).

Cycad Encephalartos lehmannii from South Africa with its one cone

(South African National Biodiversity Institute)

Pine cones come in many sizes and shapes. Sizes range from 2.5-5 cm (1-2 inches) to >50 cm (>20 inches). They can be long and slender or rounded or oblong. Some have thin parts (bracts, see below), while others are thick and look almost like a wood carving. Many have single cones growing independently, others have pretty clusters, and others like Lodgepole pine (Pinus contorta) show twisted groupings.

Various shapes and groupings of pine cones.

Top left, white pine; Top middle, Coulter pine; top right, Lodgepole pine.

Bottom left, Scots pine; bottom center, Bosnian pine; bottom right; Ponderosa pine.

Images from AZ Animals.

Some remain closed until humidity or moisture conditions are right. One, the Lodgepole pine, opens only after fire exposure. 

There are male and female pine cones. Males are smaller than females, and they tend to hang from lower branches while females are higher. Since they produce pollen, they are also called pollen cones. They are also lighter in color and softer. They fall off every year. On the other hand, female cones are hard and woody, and they produce seeds, so they care sometimes called woody cones or seed cones. They take 2–3 years to mature, stay on the tree after releasing seeds, and may remain attached for several years (decades for Lodgepole pine).

Male and female cones from Doublas fir (Allerma)

In true fir trees (genus Abies), the cones do not fall off whole like pine or spruce cones. After the seeds mature inside, the cone scales loosen and drop off one at a time. Seeds are released gradually, leaving just a bare central spike (the cone axis) sticking up.

Abies fir cone whole (left) and fallen apart with age (right) (Wikimedia)

With angiosperms, pollen is carried by wind, rain, insects, animals, or just close contact. But with gymnosperms, only the wind carried pollen to spaces inside the cone body (or strobilus). Notice that the leaf-like tips of the female cone body are not the seeds. They are called scales and two types are there for protection (seed scale) or support (bract scale). Both are modified leaves! 

Seeds form deep inside near the central stem of the cone, and pollen needs to get that far to meet up with the ovule to fertilize it and create a seed. When the scale opens, it allows the seed to fall out.

Diagram of female pine cone in cross section (from Libre Texts)

But female cones don't always look this open. When the air is dry, the cone scales lose moisture. As they dry, the scales shrink unevenly. This causes them to bend outward. The seeds are then released to gravity or the wind. Since this happens in dry weather, seeds have a greater change to float on the wind farther to spread the growth of more pines.

Video showing a pine cone opening as daylight dries the air

You can force pine cones to open and close yourself. Put open cones in warm water and watch them close. Or to dry them, you could heat closed ones in a microwave oven and watch them open.

The bract are very tightly bound when cones are closed. As they open, you can even hear them make a cracking or snapping sound.

 

Videos demonstrating the sound of female pine cones opening

The seeds of pine cones are sometimes edible, and in those cases they are called pine nuts. The following are pine nuts you can eat:

• Pinus pinea (Mediterranean/European variety, Italian stone pine)
• Pinus koraiensis (China, Korea, parts of Japan)
• Pinus sibirica (East Asia)
• Pinus edulis (Colorado pinyon)
• Pinus monophylla (American Southwest)
• Pinus lambertiana (sugar pine, Western United States (California, Oregon, parts of Nevada))

Many pine nuts can be eaten, but they may simply be too small to make it economical, whether on a large scale or in simple foraging in the woods by yourself. In all cases, the shells must be removed before the seed inside can be eaten.

European pine nuts after shell has been removed (Wikipedia)

Of course, many animals eat pine nuts. Squirrels, chipmunks, birds like crossbills, woodpeckers, and jays, even bears are the main foragers. They are all after the fiber and nutrients in the seeds, such as 

• Vitamin K
• Manganese
• Protein
• Thiamin
• Zinc
• Phosphorus 
• Magnesium

Pine nuts also contain 670 kcal/100 grams, 13–14 g of protein/100 grams, 68 g of fat/100 grams (mostly unsaturated heart-healthy, but also some polyunsaturated and monounsaturated),  13 g of carbohydrate/100 grams, and a fatty acid like pinolenic acid.

If you want to collect pine nuts in the forest, here is one video to show how it can be done with a gentle method. Here is another video with a bit harsher method. Both offer some good tips that the other one doesn't. 

Screenshots from the two videos above

Squirrels tend to eat green immature female cone seeds, but they will eat mature nuts, too. The immature seeds are more tender. And, with green cones, there is less chance that some of the seeds might have fallen out of the cone, so they get more per cone!

Upper cone uneaten, bottom cone completely eaten (Discover Wildlife)

Did you know that squirrels might be considered left- or right-handed? You can tell by the way they pick at a cone vs hold it as they eat. The hand rolling the cone is what is used to judge lefthandedness or righthandedness. The other one merely steadies it. According to one website, "Squirrels will start at the bottom and work their way upwards in a spiralling motion. If the spirals go [counter]clockwise then they are left handed, and if they go clockwise then they are right handed!" Other researchers at the Universidad Autónoma de Madrid classified 893 pine cones they found as "left-gnawed" or "right-gnawed". The type of cone didn't matter, but populations of red squirrels only 30 km away from each other were either lefties or righties.

This squirrel appears to favor his right paw to turn the cone.

Researchers from the State University of New York also learned that the farther away a squirrel is from its home, the shorter time it takes to each nuts. When they ate 200 seeds 5 meters (16.5 ft.) from cover, they held each seed for a little over five seconds, but when they were 15 m (50 ft.) from cover, they handled each seed for less than two seconds. That's not their idea of "fast food", but more closely related to self-preservation. Sitting in the open further from cover is more dangerous.

Data from the study described above. Handling time in seconds.

Recipes for human consumption of pine cones are more numerous than you might think. 

A Russian recipe for jam boils them for 30 min, allows them to sit for 12 hours, then removes the cones and adds sugar. A few finishing touches produces a thick jam. Another recipe simply alternates cones and sugar, and over time a honey-like syrup is formed. Another chops and brews very young cones to make a tea.

This video shows how to make pickled pine cones. 

Mugolio is another sweet syrup, but this takes longer. This website has a lot of details, but essentially you just add brown sugar to green pine cones, cover, and wait a month or more.

Mugolio at different stages (Forager Chef)