August-September 2023 • Nebraskaland 23
The seeds of these needlegrasses are encased in the sharp
"spear head," which also features stiff hairs that help keep it
from slipping back out of whatever it sticks into. That spear
head is attached to a long awn, similar to a very thick hair,
which acts as the spear's shaft. As the seeds mature, they
become loose in their moorings. If a furry animal or hiker
brushes against them, those sharp points embed themselves
in fur, clothing or even skin, held fi rmly in place by the
aforementioned stiff hairs.
It's easy to imagine this tactic being very eff ective
when bison roamed most of Nebraska, covered in thick,
curly hair. Of course, it's also very eff ective on moisture-
wicking wool socks and lightweight, breathable pants
made with blends of nylon, polyester and spandex. Once
needlegrass seeds become embedded, further jostling often
pushes them further into whatever material they're attached
to until they eventually encounter the skin beneath. That's
usually when they're detected, yanked out and discarded in
a new location.
After needlegrass seeds are deposited in a new site, the
long awn (the spear's shaft) gets to display its additional
ability. The awn can repeatedly coil up and straighten as
humidity conditions fl uctuate over a period of days. As a
result, the seed can eff ectively drill itself through thatchy
vegetation and right into the soil where it can germinate and
grow.
Cockleburs
Cocklebur (Xanthium
strumarium) is a native
annual broadleaf plant
found across Nebraska
that commonly grows
in crop fi elds or along
wet habitats, often in
bare ground within
dried up wetland basins
or stream banks. Young
cocklebur seedlings,
which resemble those of
annual sunfl owers, can
release toxins into the soil
that can suppress the germination
and growth of nearby plants. The plants themselves,
including the burs, are toxic as well, so try to avoid the
temptation to eat them.
Two seeds are contained within each of the oval-shaped
burs produced by cocklebur plants in the late summer or
fall. Those burs contain hooked spines that eff ectively
latch onto fur or fabric. Typically, those burs are relatively
easy to detach from pants and socks but can be much more
intractable in longer fur or hair.
Cocklebur (Xanthium strumarium) at the Nature Conservancy's Platte River Prairies.
