The stinging nettle has thousands of hollow hairs
like tiny hypodermic needles.  
Each hair is
stiffened by silica and lime taken from the soil. Their curved 
tips are closed but the walls are very thin and snap off, when touched, 
leaving a sharp slanting point which easily punctures your skin. At the 
base of the hair is a soft bulb containing a substance which is squirted out 
by the same pressure which snapped off the point when you brushed the 
hair.  When you get a shot of this stuff, you know you’ve been stung!


****:NETTLES

People don't seem to get it through their heads that they should be 
appropriately clothed when they visit our forest preserves and expect to 
enjoy a walk through the woodlands. Woolens, tweeds, or soft-textured 
garments will be covered with burs, stick-tights and "begger Lice". 
Denims are perfect. Bare-legged people will suffer not only from 
mosquitoes, flies, thorns, briars, and possible poison ivy, but also from 
the stings of nettles.

Alistaire Cooke, writing about the American summer, said that out of 
ten people he polled, only three had even a remote idea of what a nettle 
is, It is a plant you seldom notice but you sure feel it, particularly 
among the luxuriant waist-high undergrowth in woodlands on rich black 
moist soil.

Wading through this vegetation, you may experience a stinging burning 
sensation on your legs and arms but it's hard to find the miscreant 
because its poison is not felt immediately. That poison contains the 
formic acid also present in the stings of bees and ants. The quickest 
relief is obtained by mashing the leaves of sourdock or other acid plant 
into a pulp and smearing that over your skin. The slimy juice of the 
jewelweed is another remedy.

The stinging nettle has thousands of poison-loaded hairs which 
antedated, by millions of years, the hypodermic needle and syringe 
invented by a French physician in 1853. These hairs are tiny hollow 
tubes stiffened with silica and lime taken from the soil. Their curved 
tips are closed but the walls are very thin and snap off, when touched, 
leaving a sharp slanting point which easily punctures your skin. At the 
base of the hair is a soft bulb containing a poison which is squirted out 
by the same pressure which snapped off the point when you brushed the 
hair.

That burning sensation, caused by our common nettles, lasts only about 
20 minutes and is not serious but some of the tropical species are far 
more dangerous. Their stings vary in severity from those produced by 
bees and wasps to what happens when bit by a venomous snake. One 
nettle, on Timor, causes a condition like lockjaw which may last for 
weeks or months. Another, in Java, is frequently fatal.

The Nettle Family -- and this is surprising -- includes the elms, 
hackberries, mulberries, osage orange, hops and Indian hemp or 
marijuana. However, in America, the true nettles are all herbs with elm-
like leaves. They range in height up to several feet but are quite 
variable. Some are perennials and some are annuals; some have 
opposite leaves but others have alternate leaves; some have those pesky 
stinging hairs but some do not. Nearly every part of the United States 
has one or more kinds of nettles and the Chicago region has four, two of 
which are common.

Few of you who read this are botanists. It would be difficult and foolish 
to name, described and distinguish between the different kinds of 
nettles and plants that are called nettles. Some of the latter belong to the 
Mint Family; others belong to the Nightshade Family which includes 
the "Irish" potato. In fact, one of the so-called nettles -- really a 
nightshade -- was the original food of the devastating potato beetle.

The Indians and the Europeans have many uses for nettles. In spring, 
the young shoots are used like spinach greens or boiled in soup. 
Medicines for various ailments are concocted from parts of nettles. 
They used to be one of the most important sources of fiber for sewing 
and for weaving coarse linen.

Remember this, when you do run into them: don't worry about it.

Stinging nettle (Urtica urens) can be found throughout the U.S. It is a perennial herb that
attains a height of 2-3 ft. The plant multiplies quickly due to a "creeping" root system. The
whole plant is downy, and also covered with stinging hairs. Each hair is a very sharp,
polished spine, which is hollow and arises from a swollen base. In this base, which is
composed of small cells, is contained the venom, an acrid fluid, the active principle of
which is said to be bicarbonate of ammonia. When, in consequence of pressure, the sting
pierces the skin, the venom is instantly expressed, causing the resultant irritation and
inflammation. The burning property of the juice is dissipated by heat.