Prickles and Spines

"A rose (prickle) by any other name is still a pain."
                       -Editor, 2013

The identification of the big thorns on a large tree should be straight forward.  Take my honey locust....please."  Apologies to Henny Youngman*  What we have always called a honey locust thorn is actually a spine. To get to the point sorry, naming these sharp objects becomes a thorny problem.

Now back to business.  Armature refers to all the sharp sticky things on plants that can penetrate your skin.  As described at Missouri.edu,  these sharp appendages can be divided into thorns, spines and prickles.  It all depends upon what they grew from.

Honey Locust Leaf Structures?

Technically thorns are modifications of stems or branches, such as those found on a hawthorn.  Spines develop from leaf tissue including stipules and even extensions of the leaf veins, as seen in the American holly on the left.  The armature on a honey locust is a spine, even though to all appearances it is growing from the trunk like a twig with a bad attitude.

Some botanists do not differentiate between thorns and spines as both have vascular tissue.  From the point of view of an amateur naturalist strolling the woods, the differentiation of these technically is a pain in what ever part of your body brushes up against or sits on them them.  I will chose to lump thorns and spines together rather than split them apart.

Multiflora Rose

Prickles are extensions of the plant surface (cortex and epidermis), somewhat analogous to our hair and nails, but again with a mean streak.  Examples include thistle, blackberry and rose "thorns".  The term prickle seem mild when used to describe the vicious weapons of a multiflora rose specimen whose recurved points dig further into your skin as you pull away from it.  You would think it would be happy to see you go but it seems to be saying "Stop where you are!"

So what good are armatures?  They obviously have some value or the plants wouldn't have used the energy to produce them over thousands of years.  It is postulated that they protect the plant from the browsing and chewing habits of animals. Useless structures have a way of disappearing in evolution.  When we see a structure that persists without apparent value, it may be that we just haven't figured out its value yet.

The appendix, found only in humans, is a good case in point.  After decades of removing this structure during other abdominal operations believing that "while we are here we should to prevent appendicitis", the tide is changing.  There is increasing evidence that the lymphoid tissue in the appendix, so prominent in the first years of our lives, is important in priming our immune system.  More recent reports suggest that it serves as a reservoir of good bacteria to repopulate the colon after diarrheal disease has flushed the normal flora.

The major value I find in armatures is in identifying the relative few trees and shrubs that grow them.  Finally a reason to suffer the pain - tree identification!

Black locust

• Honey locust
• Black locust
• Hawthorn
• Gum bumelia
• Common buckthorn
• Osage orange
• Callary pear (Bradford pear escapee)

More exotic examples are at ucla.edu.
http://ipm.missouri.edu/meg/2013/1/of-thorns-spines-and-prickles/

* For the younger generation, Henny Youngman was an comedian whose routine included the famous one-liner was "Take my wife—please."

Missouri Gooseberry

 

Toothed leaves of MF - Illinoiswildflowers

There is not much new to see while hiking in the valley and what there is shows little color.  I saw a few small stems with green leaves, a rarity this time of year and expected to find some invasive multiflora rose (MF) or Japanese Honeysuckle that had escaped Barb's herbicide and clippers but this was different.  The thorns were thin and straight rather than recurved like the prickles* that MF produces that dig in deeper into your clothes and flesh when you pull away from them.  A closer look at the leaves showed a distinct difference with rounded lobes rather that the toothed margins of our MF enemy.

Gooseberry stem - llinoiswildflowers

Barb identified the pictures as Missouri Gooseberry, Ribes missouriense.   The most valuable source for plants in our area is illinoiswildflowers which paid off again.  Their photographs are detailed as is their description.  Unlike the hated MF, this is a great plant with lots of benefits for nature.  

The nectar and pollen attracts bees, flies,  butterflies and even hummingbird moths.  It is a host plant for the gray comma butterfly. The fruit is eaten by birds as well as fox, skunk, squirrel and raccoons.  

The Illinois Wildflower insect table is particularly valuable in finding the gooseberry's value in nature as measured by what eats it.  There are diverse species listed including my favorite the sumac flea beetle.  "Value" is a rather artificial concept we bipeds define, trying to quantify the complex interrelation of plants and animals.

"We" arrived on the continent 9,000+ years ago, making some minor modifications.  Then the second wave of "us" from Europe in the 1500s brought the Columbian Exchange, upsetting a balance of nature that was doing quite well without our interference.  While many species were brought for food or comfort, others like multiflora rose were an attempt to add beauty.

Multiflora rose berries and prickles

Multiflora rose was one of those beautifying mistakes.  Brought here from Asia in 1866 as root stock for other roses, it was promoted in the 1930s as living fence and for erosion control, another example of what seemed like a good idea at the time.  It later was planted in highway median strips as a crash barrier, a role that continues on our ATV trails.  Our bad!

*  We discussed thorns vs. prickles in a 2013 blog and nothing has changed since then.  The short answer is that armature describes a sharp pointed appendage and includes thorns, spines and prickles.

• Thorns - a sharp pointed modified stem.
• Spine - a sharp pointed structure that is a modified leaf or stipule (outgrowth on the side of a leaf stalk (petiole).
• Prickle - a sharp outgrowth of the epidermis or bark.

Whats in a name?  (3-17-2017)
Our friend Amy raised the question of why the "goose" in gooseberry.  It appears that no one knows but there are lots of speculation about the corruption of foreign words in this wide spread fruit, including several "saucy" possibilities mentioned in Wikipedia.

References
Kentucky University publication describes the thorns, spines and prickles.
llinoiswildflowers has good information on gooseberry as well as virtually any plant in Missouri.