seeds | The Prairie Ecologist

Early autumn is a season of surprise and wonder. Colors are changing and animals are scurrying all around, trying to check off all their pre-winter tasks. For nature enthusiasts like us, it’s also a great time to appreciate the complex and sophisticated ways plants move their seeds around the world.

For example, there’s the unexpected prick of joy when you accidentally sandwich a heretofore unseen sandbur between calf and hamstring as you kneel down to re-tie your boot laces.

(I think that’s the first time I’ve ever used the word “heretofore”. I hope I used it correctly. I would have used “previously”, but when I typed it out, the spelling looked wrong for some reason. Brains are funny.)

Anyway, upon discovering the sandbur, you immediately stand back up, lick your fingers, and remove it (and its friends) from your pantleg. As you have so many times, you ask yourself why licking your fingers helps it hurt less when you grab sandburs. Surely, the surface tension of saliva can’t provide that much protection? Regardless, seeing and feeling the sandburs is a terrific way to celebrate their particular seed dispersal strategy. Hurray for nature!

After you identify a winding path that will allow you to avoid more nearby sandburs, you step forward – only then remembering that you’d stopped to tie your boots. That’s when you glance down and realize that your boot laces must have pulled loose when you walked through a patch of cockleburs a little way back. Now, a cheerful cluster of cocklebur seed pods is tangled happily in your laces like spiny little meatballs in a plate of spaghetti.

Cocklebur (*Xanthium strumarium*) along a wetland edge.

As you start to carefully extract the pods from your laces, you can’t help but marvel at the similar, but different architecture of cockleburs and sandburs. Sandburs, of course have long, straight, sharp spines protruding in every direction from their mostly-spherical core. Those spines have an impressive ability to penetrate nearly any material.

Cockleburs, on the other hand, have what look like dozens of tiny fish hooks sticking out of their football-shaped bodies. Those hooks can poke through clothing (and boot laces), but they’re more likely to snag than poke, with the little hooks acting like a bunch of tiny grasping claws. Of course, if they do manage to penetrate clothing or laces, the hooks also make it much harder to extract them. It’s a really remarkable design.

The strategies of both cockleburs and sandburs are sure effective, you think, as you continue de-tangling your laces. Also, it’s fun that both of them have “bur” in their names. That, of course, brings back memories of learning the difference between burs, stickers, thorns, and spines at some point. You obviously don’t remember what those differences are now – it’s been at least three or four years since you last looked that up and no one can be expected to retain information that long. It’s fun to know there are differences, though.

Also, it’s weird that the word bur can be spelled with either one “r” or two. You know that bur oak is definitely spelled with one, though people do insist on adding that second one, don’t they?

Apart from the name of that tree, which definitely, always has only one “r”, you recall doing a little research a while back and learning that both bur and burr are considered correct spellings in certain situations. There are burs that are seed pods and burs that are rough edges on metal and it seems to you that people argue whether those two should be spelled the same or differently. Ah well, someone will probably figure that out and then people won’t have to argue anymore.

Close up, you can see the tiny hooks on the cocklebur spines (thorns? prickles? poky things?).

Anywell, you finish removing the last cocklebur (surely not cockleburr?) from your laces and leave the pods on the ground – having done them the favor of carrying them to a new potential home. Isn’t it nice to play a helpful role in the dispersal of seeds? You’re an actual conservation hero.

Well, hero, as you proceed through the prairie (by the way, you’re walking in a prairie), you take a detour around a big patch of tick clover plants. You’re no fool, after all. Tick clovers are beautiful, important wildflowers, but their seeds are like little Velcro packets that are good reminders of where the name “tick” clover comes from. Taking on the role of a seed disperser is all fine and good, but you’re in charge of fixing supper tonight and won’t have time to both do that and scrape a load of tick clover seeds off your long-sleeved shirt. A wandering deer will surely do the tick clover dispersal without you needing to become involved this time.

Side-stepping the tick clover takes you along the boundary between the prairie and a small adjacent woodland. As you walk along that edge, a tentacle appears to lash out from beneath the trees and grabs onto your pants. Startled, you pull away, but the “tentacle” leaves behind a linear string of small sticky pods. You stumble slightly over a gopher mound, and as you catch your balance again, your leg is caught by two more of those tentacles, which turn out to be branches of the amazing stickseed plant.

Stickseed (*Hackelia virginiana*) hangs out mostly in woodlands, at least around here.

Stickseed has an even more descriptive name than tick clover. The sticky “pods” carried by the stickseed branches are, as you oddly recall, actually clusters of four little “nutlets”, each containing little barbed prickles. I dated a girl named Barb Prickle in high school, I think.

I’m joking, of course. Barb wouldn’t have given me the time of day.

Returning to the present, stickseed and its prickly nutlets are magnificent examples of nature’s innovation. You know from experience that trying to rub the little nutlets off your pants will just cause them to roll along the fabric, never loosening their grip at all. It really is a spectacular evolutionary achievement. Well, you’ve owned these pants for almost four months now, so it was probably time to replace them anyway. It’s a small (well, medium) price to pay for a front row seat to this lovely demonstration of seed dispersal mastery.

A close up of the nutlets with their tiny barbed prickles.

Stickseed seeds (and a little foxtail) on my hiking clothing.

You manage to pull one of the little nutlets loose to inspect it with the hand lens you always carry on a string around your neck. Under magnification, the little prickles sure don’t look like they’d be as sticky as they obviously are. As you’re pondering that, you turn to continue your hike and walk straight into a chest-high patch of tick clover.

Well, look at that, will you? The pattern of tick clover seed pods across the front of your shirt is really visually attractive. It’s like a free participatory public art project! (Hm – the seed pods are not really pods. What are they actually called? Loments? Loment segments? No one knows for sure.) Either way, it’s loments like this that make you really ponder the awesome power of evolution.

This is Illinois tick clover (*Desmodium illinoense*) but there are lots of species with very similar sticky seeds (or loment segments).

You’ll have to pull those whatever-they’re-called off later, of course, because any that make it to the laundry will still be attached when the shirt comes out of the dryer. Except, obviously, for a few that will detach and re-attach in fun, surprising places on other pieces of clothing. That’s ok, picking tick clover seeds off a shirt later tonight will give you something to do while you’re browsing through the internet for new pants.

Speaking of tonight, look at the time! All this marveling at the wonders of nature has taken the whole afternoon and you’d probably better get on the road so you can get home in time to make supper. You’ve got leftover pulled pork in the fridge. That, some fresh carrots, and a bag of chips will make a pretty nice dinner. Maybe you’ll even stop at the grocery store on the way home and grab a nice jar of barbed prickles to complete the meal.

I’ve been seeing a lot of brand new plants germinating from seeds during the last couple weeks. Looking at all those cotyledons (first leaves) poking out of the ground makes me reflect on the massive amount of good fortune it takes for any seed to actually turn into a new prairie plant.

Prairie dandelion seeds (*Nothocalais cuspidata*).

Seed production is a high risk, high reward strategy for plants, and even that’s a huge understatement. It takes a tremendous amount of energy for a plant to produce a flower – especially if you’re trying to make one that’s attractive to an animal pollinator. There’s all the colorful petals or other structures, nectar (in many cases), and, of course the pollen itself. After pollination, even more energy can go into loading up the developing seeds with the nutrition and energy needed to give the embedded embryo a chance of success.

Once the seeds are released from the plant, they often travel away from their parent – at least far enough that they aren’t trying to grow directly beneath them. The varied tactics used by plants to disperse their seeds is a huge, fascinating topic, which I’ve written about before. Regardless of whether a seed travels by wind, water, attached to the fur or feathers of an animal, or by being eaten and then pooped out, there are myriad dangers along the way.

Prairie violet (*Viola pedatifida*) seeds can travel in two ways. First, they are ballistically launched into the air as their pods dry and constrict. Second, many are picked up and carried home by ants because of the little fatty packet of nutrition (elaiosomes) violet seeds have attached to themselves for that very purpose.

Seeds packed with nutrients to feed their embryo are also a great food source for many other organisms. Countless vertebrate and invertebrate animals seek out and eat seeds, especially during the dormant season when most other food sources are scarce. Fungi and lots of microorganisms can also destroy and consume seeds.

If, by some minor miracle, a seed survives its short or long journey intact, it may still be a long way from ultimate success. For most plants, germination only happens if a seed is in good contact with soil. Think for a moment about the world a seed is launched into and how many obstacles there are between that seed and the soil!

When you walk through most prairies, if you look straight down, you’re not seeing a lot of bare soil. Instead, there are a lot of living and dead plant parts (leave, stems, etc.) between your feet and the ground. A recently-burned prairie, of course, has lots of bare ground. That’s a great opportunity, but only for any seeds who weren’t consumed by the fire itself.

Most seeds land on something besides soil. Often, that’s the end of their journey and they sit there until they die (e.g., the embryo runs out of stored food) or they’re found and consumed by another organism. If they’re lucky, they might get dislodged from their original landing spot by wind or rain, for example, and slip downward toward the soil.

Entire-leaf rosinweed seeds (*Silphium integrifolium*)

Let’s say a seed has led a lucky life and manages to reach soil. It might even get pushed into that soil slightly by rain or a passing animal’s foot. Hooray! Now it can grow and reward its parent’s huge investment.

Well, maybe.

Most seeds need water to germinate. During drought periods, a seed might sit in the dusty earth for weeks, months, or years, waiting for sufficient moisture to help break its seed coat open. As it sits there, it’s vulnerable to any passing animal, fungal hyphae, or tiny microorganism looking for a meal. Plus, as we discussed earlier, the embryo might simply run out of food.

Even if rain or snow provides sufficient moisture for germination, some prairie seeds also need a certain amount of sunlight to trigger germination. (This is why it’s important not to plant prairie seeds like you plant pumpkin or green bean seeds. Just scattering them on top of the ground is often best.) If a seed that requires light lands on bare soil that happens to be in the shade of other plants, it might still be stuck in limbo.

Illinois bundleflower seeds have such a strong seed coat they can survive a trip through the digestive system of an animal. That’s great for the seed, but doesn’t provide any reward for the poor hungry animal!

As a result of all the challenges they face, only a tiny percentage of seeds released into the world by their parents actually end up germinating. Those that do have a chance to perpetuate the family line. However, simply reaching the germination stage isn’t the end of the race.

A tiny seedling still has to compete with any nearby plants for food, water, and sunlight. Only a small minority of prairie plant seedlings make it to maturity and create their own flowers and seeds. They either wither and die in the face of more competitive neighbors or get eaten by herbivores looking for fresh new growth to nibble on.

Despite the odds, of course, some seeds do manage to germinate and then become parents themselves. We’ve got abundant evidence of those successes all around us. It’s easy, though, to take those winners for granted. Spare a thought for all those who didn’t make it!I’m cheering on all the little germinating plants in the prairie right now. They’ve already survived a ton of obstacles, but they still have a lot to overcome.

I often wish seeds good luck when I see them, too (usually silently, especially if other people are around). While most seeds fail to become plants, each one of them plays a vital role in the prairie ecosystem. Animals and other organisms have to eat, after all, and seeds help keep lots of other community members alive.

Apart from everything else, seeds and the structures that help carry them into the world are simply beautiful. I’m incredibly appreciative of the diversity and aesthetic elegance of prairie seeds and I’ve spent a lot of joyful hours photographing them. I just try not to dwell too much on their individual survival chances…

The Prairie Ecologist

Essays, photos, and discussion about prairie ecology, restoration, and management

Tag Archives: seeds

Celebrating Sticky Seeds

Celebrating Seeds