Nebraskaland

22 Nebraskaland • August-September 2023 them fl oat away on a breeze to seek their fortune elsewhere. Plants can often create hundreds or thousands of those tiny wind-dispersed seeds per year, and while most still fall to the ground or get stuck in vegetation close to their parents, a few may travel many miles. Wind dispersal sounds like a terrifi c strategy until you realize that to reduce weight, seeds can't carry much food within their seed coat. That means they don't have long to hit the soil and germinate before they die. They also have a thin seed coat, which means they are vulnerable to damage from temperature extremes, digestion by animals and other threats. As a result, the risk for an individual seed is extraordinarily high. On the other end of that spectrum, there are plants that give their seeds heavy-duty protective coverings and try to attract animals to eat them. In most cases, those seed coats can protect the integrity of the seed as it passes through an animal's digestive tract, and it can emerge and be deposited far away from where it was consumed. You might say those seeds are both heavy-duty and heavy-in-doody. You probably shouldn't, though. Making large seeds with robust seed coats, however, takes a lot of resources from a plant. That investment increases even more when a plant wraps its seed in a sweet, fl eshy fruit to entice a robin or raccoon to make a meal out of it. As a result of that high cost, plants generally don't make very many of those seeds. The few seeds they do create have a relatively high chance of surviving their journey, but there's still a huge risk that none will be deposited where they can germinate and grow to adulthood. Seeds that can hitchhike on animals (or human hikers) kind of split the diff erence between those other two strategies. They tend to be larger and more robust than wind-dispersed seeds, but the investment in their construction is much less than is needed to create a plum or raspberry. In most cases, the plant simply adds some spines, hooks or other similar appendages to the seed coat or seed pod. The variety found within those attachment features is incredible. Hitchhiker seeds can latch onto a passing animal's coat (or pants, as applicable) when that animal brushes up against them. They then get carried until they're dislodged, either intentionally or unintentionally. Sometimes, there's a very short period between attachment and detachment ("Ouch! What is that? Get it off me!"). More often, the seed's courier doesn't realize it has passengers until it has moved a fair distance away. In fact, many seeds are brushed off before an animal even knows they were there — dislodged as the animal scrapes against other vegetation or rolls around in the dirt for a nice, pleasing dust bath. There are lots of plants that equip their seeds with hooks, spines or other features that help them hitchhike on animals, including humans. Here are six plants that Nebraska outdoor enthusiasts are likely to encounter. Each has its own unique characteristics, worthy of your appreciation. Needlegrasses Needlegrasses (Hesperostipa sp) are perennial grasses that bloom in late May and early June across Nebraska. Two, in particular, have seeds that resemble long spears with sharp points. Needle-and-thread grows mostly in sandy soil and can be found throughout the northwestern two- thirds of the state. Porcupine grass (illustration, right), which has even larger "spears," is in the northeastern two-thirds of the state, meaning that in much of central Nebraska, you might fi nd both. Needle-and-thread grass seed (Hesperostipa comata) at the Nature Conservancy's Platte River Prairies in Hall County.

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