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Well I was wondering this as I was chipping up dead Himalayan blackberry briars in my wood chipper today?Do they serve any other purpose nutritional water wise or other beneficial service to the plant?
Yes thats what I mentioned in the title!
Quote from: Karen W. on 02/04/2009 03:08:40Yes thats what I mentioned in the title!Ahhh yes, I seemed to have missed that detail in my haste to post my answer. One must consider the selective nature of this defense mechanism however. The berries and pollen are attractive to many species as a food source, thereby insuring that the pollen and seed will be carried to new locations. The function of the thorns must inhibit damage caused by larger and more clumsy creatures in favor of the smaller and more agile ones, thereby increasing the likelyhood for less damage while still insuring the pollination process and dispersion of seed.
I tought they were modified leaves,
There are very few genuine 'climbing' plants, most of those we have as climbers are in fact ramblers. Today's climbing, tea, floribunda and bush roses are hybrids of the natural ramblers. These ramblers like the brambles (blackberry) use the prickles on individual stems to help interlock the stems to each other and to the stems of other bushes to keep them off of the ground. This way the new growth can get high up to where there is the most sunlight without the need to expend to much energy on the growth of a rigid trunk. From this high vantage point, they can then spread over greater distances. As I am sure you will be aware, trying to pull out a single stem of bramble is virtually impossible.As to your question 'What makes the thorn so much harder and stiffer then the stem itself?' I'm afraid I cannot help on that point (no pun intended). I'm not even sure the reasons are known to botanists. Perhaps someone should ask David Belamy.
I'm not David Bellamy, but I do have a bushy beard so perhaps I can anaswer this.Anyone who has got a splinter from a piece of rough timber will know that wood is hard enough to make spikes that can puncture skin. My guess is that the thorns (and BTW, I tought they were modified leaves, but I may be getting them muddled with needles) are made essentially of celulose and lignin. The reason that they are stiffer than the stem is because it's expensive for the plant to make lots of lignin and cellulose so, for the stems, it doesn't make much but, if the thorns are not rigid then there's no point having them (no pun intended).
Quote from: Bored chemist on 02/04/2009 19:59:20I tought they were modified leaves, If dhis is the Oirish in you coming out, I tort it was spellede loike dhat, big orro (Irish Frankenstein). Or did you just have an attack of slippery finger on keyboard?Some leaves can be very sharp, but I do not think they are classified as prickles or thorns. Leaves can bear prickles, the rose is a good example of this, or sharp rigid hairs, as on the stinging nettle. Unlike the soft hairs on some plants, these are reinforced with silicates or carbonates. See this cross section of a rose prickle http://www.biologie.uni-hamburg.de/b-online/e05/stachel.htm
Some sharp projections on plants are modified stems, some modified leaves, and some are outgrowths of the epidermis, the 'skin', of the plant.
Lignin is a complex polymer in plant cell walls that gives the plant rigidity and strength, and is the major component of wood.
Sorry, I know I shouldn't have posted that, but I just couldn't resist it.
Quote from: Don_1 on 09/04/2009 12:14:59Sorry, I know I shouldn't have posted that, but I just couldn't resist it.hmmm
Quote from: dentstudent on 09/04/2009 12:21:35Quote from: Don_1 on 09/04/2009 12:14:59Sorry, I know I shouldn't have posted that, but I just couldn't resist it.hmmmWith no opss, your post doesn't count.