The Mystery of the Thorny Plants

There are two types of thorny plants in my yard, but for today I'm going to focus on one of them - the thorns in my side, if you will.  In the above picture, you can probably spot the well-worn deer trail just to the right of center.  To the left of the deer trail, and to a lesser extent to the right of it, are the thorny plants.  Now, it's a bit deceptive, because they're leafy, but you might be able to make out the purplish stems (or canes, as I found out they are called) arcing back down toward the ground.  (Incidentally, if you can see the green-stemmed plant right in front of the tree, with stems arching out in opposite directions, that is the second type of thorny plant.)  Note the difference in the photo below, which I took after removing most of the thorny plants.  The vegetation has been thinned out considerably.  (Of course, it also looks different because the fallen leaves are covering much of the shorter grass and weeds.)  Toward the upper left of the photo, to the left of the tree trunk, is another patch of thorny plants that I have yet to get to.

And here's a thorny plant up close. They're distinguishable by their purplish canes (stems) and those bright green leaves.

As I was working to eradicate these thorny plants from the garden, and later as I worked on this little patch of land near the deer trail, I began learn how these annoying buggers operate.  As you can see above, they can spread out in multiple directions from their launching point.  The shoots first grow straight up, without thorns (as I showed in a photo yesterday), but eventually the cane thickens and develops thorns, as it bends back down toward the ground.  When a thorny plant cane hits the ground, it begins to lay down roots.  These roots appear to grow pretty quickly, as even a thin cane-end can be attached to a well-developed root system, as shown below.  This new root can then become a new launching off point for more canes, as these aggressive plants march ever onward in their efforts for the conquest of my yard.

These thorny plants are stubborn, as they will grow pretty much anywhere.  See the purple shoot coming straight out of the short tree trunk in the photo below?

Now that I had a pretty good idea how these thorny plants operated (and I wasn't thrilled about it), I wanted some expert advice on how to handle them.  But first I had to know what they were.  I had also seen thick, dead vines and other, larger weeds (also dead) that had grown next to some of the trees in the yard.  (More on these in a later post.)  My fear was that these thorny plants were the pre-cursors of even larger plants that could cause even more damage.  In that strange state between sleep and wakefulness, I had terrible nightmares of evil super-plants bent on the destruction of my backyard.  I had gone from cautious optimism that these thorny plants might have some useful purpose in my yard's ecosystem to outright fear that they were no good at all.  Clearly, I needed a dose of reality.

I sent one of the above pictures to Craig Cramer, who works for Cornell's Department of Horticulture, and who runs an excellent garden blog, Ellis Hollow.  Now, I was expecting to hear that this was some evil, invasive plant from overseas with some stark name like Purple Death.  His reply was not at all what I was expecting...he suggested that these evil, thorny plants were wild raspberries.  I did some research on the web, and it turns out that these are indeed most likely wild black raspberry plants.  Of course, I had missed the flowering and berry stages because they happen in late spring to early summer, and I didn't move here until August.

Here's a little more information, based on a little web research, about wild black raspberries.  Wild raspberries prefer plenty of sunlight (which is probably why they thrive in that far corner of the yard) and slightly acidic soil.  They like to have plenty of organic matter in the soil, which is the case in the part of the yard that they are threatening to overrun.  Though the roots and crowns of the plants are perennial, individual canes first develop in the spring and live for two years.  The canes produce berries in the second year, then die shortly after.  Black raspberries are susceptible to extremely cold temperatures: they'll die if the thermometer drops below 5 degrees Fahrenheit.

Of course, the question now is, do I want them in my yard?  On the one hand, I want berry plants in the yard to attract birds, and if these wild raspberry plants make the yard active with berry-loving birds for part of the year, it could be nice to have them around.  But on the other hand, I'm looking for a yard that's relatively easy to maintain over the long run, and with their wildly aggressive tendencies, wild raspberries don't necessarily fit that bill.

So the plan for now is to clear out some patches of wild raspberries, leave others in place, and see what happens when the berries ripen in May/June.  If there's a frenzy of bird activity, it may be worth keeping a wild raspberry patch in a secluded corner of the property.  And if not, well, so much for wild raspberries...

Source:

http://umaine.edu/publications/2066e/