Pine Cones Are Like Hangars for Pine Tree Seeds

Over the past year I’ve written about the making of pine tar and the drinking of pine needle tea. But why stop there? Pines are a fascinating group of plants, worthy of myriad more posts, and so my exploration into the genus continues with pine cones and the seeds they bear.

Pines are conifers and, more broadly, gymnosperms. They are distinct from angiosperms (i.e. flowering plants), with the most obvious distinction being that they don’t make flowers. Since they are flowerless, they are also fruitless, as fruits are seed-bearing structures formed from the ovary or ovaries of flowering plants. Pines do make seeds though, and, as in angiosperms, pollen is transported from a “male” organ to a “female” organ in order for seeds to form. Rather than being housed in a fruit, the seeds are essentially left out in the open, which is why the term “naked seeds” is frequently used in reference to gymnosperms.

seed cone of Scots pine (Pinus sylvestris ‘Glauca Nana’)

In the case of pines and other conifers, the seeds may be naked, but they’re not necessarily homeless. They have the protection of cones, which is where the female reproductive organs are located. Male, pollen cones are separate structures and are smaller and less persistent than the cones that house the seeds. A cone, also known as a strobilus, is a modified branch. A series of scales grow in a spiral formation along the length of the branch, giving the cone its shape. On the inside of these scales is where the seeds form, two per scale. First they are egg cells, and then, after pollination and a period of maturation, they become seeds. The scales protect them throughout the process and then release them when the time is right.

With more than 120 species in the genus Pinus, there is great diversity in the size, shape, and appearance of pine cones. While at first glance they don’t appear all that different from one another, the cones of each species have unique characteristics that can help one identify the pine they fell from without ever having to see the tree. Pine cones are also distinct from the cones of other conifers. For one, pine cones take at least two or, in some cases, three years to reach maturity, whereas the cones of other conifers develop viable seeds in a single year. Pine cones are also known to remain on the tree for several years even after the seeds are mature – in some species up to 10 years or more – and they don’t always part with their seeds easily. Lodgepole pines (Pinus contorta) require high temperatures to melt the resin that holds their scales closed, the cones of jack pine (P. banksiana) generally only open in the presence of fire, and the seeds of whitebark pine (P. albicaulis) are extracted with the aid of birds (like Clark’s nutcracker) and other animals.

immature seed cone of lodgepole pine (Pinus contorta)

Every pine cone is special in its own right, but some stand out in particular. The largest and heaviest pine cones are found on Coulter pine (P. coulteri), measuring up to 15 inches long and weighing as much as 11 pounds with scales that come to a sharp point. It’s understandable why the falling cones of this species are frequently referred to as widowmakers. Longer cones, but perhaps less dangerous, are found on sugar pine (P. lambertiana). The tallest trees in the genus, the cones of sugar pine consistently reach 10 to 20 inches long and sometimes longer.

Pine tree seeds are a food source for numerous animals, including humans. Most are so small they aren’t worth bothering with, however, several species have seeds that are quite large and worth harvesting. Most commercially grown pine nuts come from stone pine (P. pinea) and Korean pine (P. koraiensis). In North America, a wild source for pine nuts is found in the pinyon pines, which have a long history of being harvested and eaten by humans.

immature seed cone of ponderosa pine (Pinus ponderosa)

The seeds of many pines come equipped with little wings called samaras, which aid them in their dispersal. Upon maturity, pine cone scales open and release the seeds. Like little airplanes leaving the hangar, the seeds take flight. Wind dispersal is not an effective means of dispersal for all pines though. A study published in Oikos found that seeds weighing more than 90 milligrams are not dispersed as well by wind as lighter seeds are. When it comes to long distance dispersal, heavier seeds are more dependent on animals like birds and rodents, and some pines rely exclusively on their services. The author of the study, Craig Benkman, notes that “bird-dispersed pines have proportionately thinner seed coats than wind-dispersed pines,” which he points out in reference to Japanese stone pine (P. pumila) and limber pine (P. flexilis), whose seeds weigh around 90 milligrams yet rely mostly on birds for dispersal. Benkman suspects that the seeds of these two species “would probably weigh over 100 milligrams if they had seed coats of comparable thickness as wind-dispersed seeds.”

Whitebark pine, as mentioned above, holds tightly to its seeds. Hungry animals must pry them out, which they do. Pine seeds are highly nutritious and supplement the diets of a wide range of wildlife. Some of the animals that eat the seeds also cache them for later. Clark’s nutcrackers are particularly diligent hoarders, harvesting thousands more seeds than they can possibly consume and depositing them in small numbers in locations suitable for sprouting.

Even large seeds that naturally fall from their cones have a chance to be dispersed further. As the seeds become concentrated at the base of the tree, ground-foraging rodents gather them up and cache them in another location, which Benkman refers to as secondary seed dispersal.

Particularly in pine species with wind dispersed seeds, what the weather is like helps determine when the hangar door will open to release the flying seeds. When it is wet and rainy, the scales of pine cones close up. The seeds wouldn’t get very far in the rain anyway, so why bother? When warm, dry conditions return, the scales open back up and the seeds are free to fly again. You can even watch this in action in the comfort of your own home by following the instructions layed out in this “seasonal science project.”

immature seed cones of limber pine (Pinus flexilis)

mature seed cones of limber pine (Pinus flexilis)

Further Reading:

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Photos of pine cones were taken at Idaho Botanical Garden in Boise, Idaho

Drought Tolerant Plants: Yellowhorn

A drought tolerant garden doesn’t have to be treeless. While the pickings are slim, there is a selection of trees that, once established, are well adapted to deal with extended bouts of little to no water. One such tree is yellowhorn, a species that demands to be considered for any waterwise landscape. Yellowhorn is rare in cultivation – and also restricted in its natural distribution – but perhaps that will change as word gets around about this beautiful and resilient tree.

Xanthoceras sorbifolium is native to several provinces in northern China and has been cultivated in a number of places outside of China since at least the 1800’s. Its ethnobotanical value is well understood in China. Its leaves, flowers, and seeds are edible and medicinal, and the high oil content of its seeds make them useful for the production of biofuels. Researchers are also investigating the use of yellowhorn for ecological restoration in arid habitats where desertification is a concern.

yellowhorn in bloom

Yellowhorn is the only species in the genus Xanthoceras, but is one in a long list of trees and shrubs in the Sapindaceae family – a family that now includes maples and horse chestnuts. It is considered both a large shrub and a small, multi-stemmed tree. It reaches a maximum height of about 25 feet, but arrives there at a relatively slow pace. It tolerates a variety of soil types, but like most other drought tolerant plants, it prefers soils that don’t become waterlogged easily. Its leaves are long, glossy green, and compound, consisting of 9 – 17 leaflets. The leaves persist late into the year and turn yellow in the fall. However, late spring, when the tree is covered in flowers, is when this tree puts on its real show.

Large white flowers with yellow-green centers that turn maroon or red-orange as they age are produced on racemes at the ends of branches. Small, yellow, hornlike appendages between each of the five petals of the flowers are what gives the tree its common name. Flowering lasts for a couple weeks, after which fruits form, which are about 2.5 inches wide, tough, leathery, and somewhat pear shaped. In my experience, most of the fruits are eaten by squirrels long before they get a chance to reach maturity. The ones the squirrels don’t get will persist on the tree, harden, and eventually split open to reveal several large, dark, round seeds nestled in chambers within the fruit.

To truly appreciate this tree, it must be seen in person, especially in bloom. At that point you will demand to have one (or more) in your garden. The seeds are said to be delicious, so you should give them a try if you can beat the squirrels to them. For a more thorough overview of yellowhorn, check out this article from Temperate Climate Permaculture, and for more photos of yellowhorn in bloom, check out this post from Rotary Botanical Gardens.

Squirrel nesting in yellowhorn, getting ready to go after more fruits.

All photos in this post were taken at Idaho Botanical Garden in Boise, Idaho.

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More Drought Tolerant Plants Posts:

Party Time for Puncture Vine, Year Two

Party Time for Puncture Vine, Year Two

A noxious weed brought Boiseans together for the second year in a row. After a successful inaugural year, the Boise Goathead Fest returned to downtown Boise, Idaho on the 2nd and 3rd of August. The festival’s namesake comes from a particularly destructive weed whose spiky fruits are notorious for puncturing bike tires. Known commonly as goathead or puncture vine, Tribulus terrestris is abundant in the Treasure Valley and the bane of area bicyclists. Organized by the Boise Bicycle Project and other bike-centric non-profits, Boise Goathead Fest is a celebration of bike culture, as well as an opportunity to spread awareness about this problematic plant.

goathead-themed art

For the two months leading up to Goathead Fest, Treasure Valley residents were encouraged to pull as many goatheads as they could get their hands on. Those who took on the challenge were rewarded with tokens to be redeemed at the Fest for drinks or ice cream. Trophies and prizes were also presented to those who pulled the most goatheads over the two month period. This effort resulted in thousands of pounds of goatheads being removed from the area, saving bicyclists from countless flat tires and slimming down puncture vine’s extensive seed bank.

scale for weighing goathead collections

After two months of collecting goatheads, it was time to celebrate. The two day long party consisted of live music and DJs, a huge bike parade around downtown Boise (for which participants were encouraged to decorate their bikes and wear costumes), and a variety of other bike-themed and non bike-themed activities. Goathead education continued during the Fest with the help of folks from Ada County, City of Boise, Idaho Botanical Garden, and others.

A peak inside the Ada County Weed, Pest, and Mosquito Abatement education and outreach trailer

Goathead coloring page created by Wendy of Idaho Botanical Garden

Puncture vine pennants created by Anna of Idaho Botanical Garden

With all of this attention and awareness focused on a single noxious weed, might it be possible to eliminate it from our community and free ourselves from ruined rides and trashed tires? The seeds of puncture vine are relatively short lived, and as an annual plant, seeds are its only method of reproduction. Even if we can’t altogether eliminate it, we could certainly see a dramatic reduction in its abundance and distribution. Perhaps in the future we will spend less time pulling it and more time celebrating its rarity, reflecting back on the time when punctures permeated our pedal-powered lives. Whatever the result, puncture vine has brought our community together once again. If such a loathsome weed can bring people together in celebration like this, perhaps it’s not entirely bad.

me with goathead balloon

See Also: Boise Weekly – Goathead’s the Burr, Community’s the Word

Selections from the Boise Biophilia Archives

For a little over a year now, I’ve been doing a tiny radio show with a friend of mine named Casey O’leary. The show is called Boise Biophilia and airs weekly on Radio Boise. On the show we each take about a minute to talk about something biology or ecology related that listeners in our local area can relate to. Our goal is to encourage listeners to get outside and explore the natural world. It’s fascinating after all! After the shows air, I post them on our website and Soundcloud page for all to hear.

We are not professional broadcasters by any means. Heck, I’m not a huge fan of talking in general, much less when a microphone is involved and a recording is being made. But Casey and I both love spreading the word about nerdy nature topics, and Casey’s enthusiasm for the project helps keep me involved. We’ve recorded nearly 70 episodes so far and are thrilled to know that they are out there in the world for people to experience. What follows is a sampling of some of the episodes we have recorded over the last 16 months. Some of our topics and comments are inside baseball for people living in the Treasure Valley, but there’s plenty there for outsiders to enjoy as well.

Something you will surely note upon your first listen is the scattering of interesting sound effects and off the wall edits in each of the episodes. Those come thanks to Speedy of Radio Boise who helps us edit our show. Without Speedy, the show wouldn’t be nearly as fun to listen to, so we are grateful for the work he does.

Boise Biophilia logo designed by Sierra Laverty

In this episode, Casey and I explore the world of leaf litter. Where do all the leaves go after they fall? Who are the players involved in decomposition, and what are they up to out there?

 

In this episode, Casey gets into our region’s complicated system of water rights, while I dive into something equally complex and intense – life inside of a sagebrush gall.

 

In this episode, I talk about dead bees and other insects trapped and dangling from milkweed flowers, and Casey discusses goatheads (a.k.a. puncture vine or Tribulus terrestris) in honor of Boise’s nascent summer celebration, Goathead Fest.

 

As much as I love plants, I have to admit that some of our best episodes are insect themed. Their lives are so dramatic, and this episode illustrates that.

 

The insect drama continues in this episode in which I describe how ant lions capture and consume their prey. Since we recorded this around Halloween, Casey offers a particularly spooky bit about garlic.

 

If you follow Awkward Botany, you know that one of my favorite topics is weeds. In this episode, I cover tumbleweeds, an iconic western weed that has been known to do some real damage. Casey introduces us to Canada geese, which are similar to weeds in their, at times, overabundance and ability to spawn strong opinions in the people they share space with.

 

In this episode, I explain the phenomenon of marcescence, and Casey gives some great advice about growing onions from seed.

 

And finally, in the spring you can’t get by without talking about bulbs at some point. This episode is an introduction to geophytes. Casey breaks down the basics, while I list some specific geophytes native to our Boise Foothills.

 

The Dragon of Yankee Fork: Spalding Viaduct

This is a guest post by Martha Dalke Hindman. It is an excerpt from her upcoming book, The Dragon of Yankee Fork. This is the final of three posts. See also: Devil’s Washbasins and Grave Markers.

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Spalding Viaduct, from the Old Mission site over the Railroad tracks
Built in 1924, steel rods, concrete construction, supporting arches and pillars.
570 feet long, 20 feet wide, a Link in U.S. Highway 95 connecting Idaho, North to South.
Today, a Chain Link Fence and Steel Gates surround the structure.

Black Locust trees, cascading white or lavender flowers
Compound leaves, dark brown seed pods.
Shade and shelter for family picnics and softball games
Beside the Spalding Viaduct, the Nez Perce Tribal Cemetery

black locust (Robinia pseudoacacia)

Travel with my Dad was always an adventure. However, the Spalding Viaduct on U.S. Highway 95, was the scariest stretch of concrete highway, we ever encountered.

Dad slowed to a stop as we approached the Spalding Viaduct. A semi tractor-trailer rig was traveling north and in the center of the viaduct, leaving no room for any other vehicles. I watched as the driver carefully drove his rig down the narrow span. The driver slowed, saluted his “thanks” to us, and continued his journey. Normal traffic, backed up at either end of the viaduct, continued to their destinations. Dad and I were on our way to Boise – Idaho’s Capitol City.

Dad continued the story about how the Spalding Viaduct on U.S. Highway 95 connects the State of Idaho, North to South and South to North.

“The Spalding Viaduct is the vital link for travelers to stay within the geographical boundaries of the State of Idaho. Otherwise, to reach Boise from Lewiston, travel west and south on U. S. Highway 12 to Walla Walla, Washington, cross the Columbia River south to Umatilla, Oregon Highway 82. Outside Umatilla, connect with U.S. Highway 84 east through Southeast Oregon, across the Snake River at Ontario, Oregon and into Boise. The only other way to reach Boise from our home in Moscow, is to travel south on U.S. Highway 95 to Lewiston, turn east on U.S. Highway 12 into Hamilton, Montana. From Hamilton, south on U.S. Highway 93 through the magnificent Bitterroot Valley, to the Montana, Idaho border. U.S. Highway 15 takes you to Idaho Falls and U.S. Highway 86 into Boise. Coming from our home in Moscow, travel time to Boise would be two days. That is why the Spalding Viaduct is so vital to North-South and South-North traffic.”

“Dad, do we change time zones before we reach Boise??”

“Yes, Martha Lee. Time zones change from Pacific Standard Time, to Mountain Standard Time when we cross the Salmon River Bridge at Riggins. Because we are traveling south, we lose one hour. Watch for a roadside park with a picnic table. Mother packed a lunch full of sandwiches, goodies and a thermos full of ice cold water. We should arrive in Boise about 7 pm. Mountain Standard Time. In the meantime, enjoy the scenery.”

“Dad, there is JUST the place for our picnic, under the shade of the black locust trees.”

We parked our car at the picnic area next to the Spalding Viaduct. The black locust trees in bloom, a gentle breeze brought “fishy” smells from the Clearwater River, the water still high and rapid from the spring rains. The log drive was finished, only a few pieces of debris floated by.

Several families were finishing their noon meal, as we sat down at the long wooden table and unpacked our lunch. Mother had prepared peanut butter and honey sandwiches, potato salad, liverwurst slices, cheddar cheese, carrots and strawberries from our garden, chocolate chip cookies, and a large Coleman thermos of cold water. What a feast!

The afternoon sun was warm, the breeze calm, just the recipe for a game of softball. Dad batted first. A gentle swing to left field. Home Run!!

My turn to bat! I swung, missing the first ball. The second pitch, I hit, but it flew straight into the Clearwater River. The strong current carried my softball downstream. I could not catch it. End of Game!

I cried. Dad put his strong arms around my sagging shoulders. “It’s OK, Martha Lee. I’ll see to it that you have another softball. We will never know how far your old ball will travel. It may get stuck in debris along the river banks, or it may end up in the Pacific Ocean, riding the ocean currents to the shores of the Hawaiian Islands, or maybe even into Shanghai Harbor, China!”

Several days later, Dad came home with a package under his arm. With a twinkle in his eye, Dad gave me the box. I opened the shiny, square box. Inside was a new softball ready to be played with and loved just as much as the old one.

Thanks, Dad.

Additional Information:

The Spalding Viaduct is falling apart, literally. Large pieces of the concrete columns become loose and fall to the ground. This once vital link on U.S. Highway 95 is closed with steel gates and a chain link fence. Moss grows where semi trucks carrying goods and produce South to North and North to South, passenger cars and buses, traveling South to Boise and North to Canada, watched out for each other on the narrow roadway.

Modern day travelers and truck traffic continues to travel North-South and South-North on U.S. Highway 95, over a new bridge (built in 1962) across the Clearwater River to the East of the Spalding Viaduct. A new stretch of highway was constructed from the river bridge, over the railroad tracks, up the hill, and onto the Camas Prairie. U.S. Highway 95 continues south to Grangeville, Riggins, and ends at Middleton, Idaho. U.S. Highway 44 connects with U.S. Highway 84 into Boise.

Updates were made to the current bridge in 2014. Click here for more information.

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Poetry, personal stories, images, journal entries, recipes for Springerle, Cinnamon Rolls, Fried Cakes, “a little bit of science thrown in for good measure,” print and online resources, all define “The Dragon of Yankee Fork,” an Idaho Alphabet from A to Z. It all began on a long piece of cream colored shelf paper! (Visit the Go Fund Me page to learn more about the project and contribute to its creation.)

Martha Dalke Hindman’s outdoor classroom was the travel adventures she shared with her father around the State of Idaho. From dusty roads, fishing expeditions, and a keen sense of observation, learning about Idaho’s heritage gave Ms. Hindman her voice in poetry and personal short stories. She may be reached at martha20022 [at] gmail [dot] com.

2018: Year in Review

Another year has passed, which means it’s time again for a Year in Review. As I have done in the past, I am including links to a selection of posts that came out in 2018. Most of these posts are part of ongoing series. You can find the rest of the posts from 2018 in the Archives widget on the right side of the screen (or at the bottom of the page if you are viewing this on a mobile device).

Among many memorable happenings this year, the one I feel most compelled to highlight here is a short radio show that a friend and I started doing on Radio Boise, our community radio station. The show is called Boise Biophila, and each week Casey O’Leary and I spend about a minute each talking about something biology or ecology related with the goal of encouraging people to get outside and take a closer look at the natural world around them. After the shows air, I put them up on our Soundcloud page for all to hear for years to come. You can follow us there, as well as on our Facebook page.

Ficus carica via PhyloPic

In the spring of 2018 we set up a Donorbox account, which is a simple way for people who enjoy Awkward Botany and want to see it continue to give us a little financial encouragement. We received several donations at that time, and we are very grateful to those that contributed. But just like public radio or any other organization that would like to receive your support in the form of money, we continue our plea. If Awkward Botany means something to you and you feel compelled to share some of your hard-earned dollars with us, we are happy to receive them and promise to put them to good use.

Donate

Money aside, a major contribution you can make to the success of Awkward Botany is to share it with your friends. Spread the word in conversation, through the postal system, over the phone, or through one or more of the myriad social media platforms. However you choose to share is none of our business. We are just happy that you do.

You are also encouraged to follow our various social media pages: Twitter, Tumblr, and Facebook. Above all, keep reading. We have lots more posts in the works for 2019, and we wouldn’t want you to miss out on the fun. Our appreciation for plants and the natural world is a constant, and we hope you will continue to share in our botany nerd revelry throughout the coming year.

Fragaria vesca via PhyloPic

Book Reviews:

Botany in Popular Culture:

Tiny Plants:

Field Trip:

Eating Weeds:

Two-parters:

Guest Posts:

More Urban Botanical Art

Two years ago I shared my first collection of urban botanical art photos. Since that time I have collected several more. I had hoped to get lots of photos during my trips out of town, and while I did manage to get a few, it turns out that my hometown of Boise, Idaho has a sizable (and growing) selection of plant-related public art. Thus, several of these are local finds.

As I mentioned in the original post, if you have photos of urban botanical art that you would like to share with me, please do so either through twitter, tumblr, facebook, or some other means.

Utility box on the corner of 13th and River Streets in Boise, Idaho

Utility box on American Legion Boulevard in Mountain Home, Idaho

Downtown Anchorage, Alaska

Downtown Anchorage, Alaska

Restrooms at the edge of Warm Springs Golf Course in Boise, Idaho. All plants represented are native to Idaho.

A plaque featuring botanical and common names accompanies each plant. 

Sculpture at Richmond Nature Park in Richmond, BC, Canada

In the Food Garden at UBC Botanical Garden in Vancouver, BC, Canada

Reverse-Rebirth sculpture by Han Seok Hyun at Idaho Botanical Garden in Boise, Idaho

Paintings of flowers displayed outside of Boise Creative Center in Boise, Idaho

Utility box on the corner of Myrtle Street and Broadway Avenue in Boise, Idaho

Downtown Mountain Home, Idaho (Community Canvas of Moho)

Mural by Stephen Murphy (my dad!) in downtown Mountain Home, Idaho (Community Canvas of Moho)