Both common and glossy buckthorn are absolutely, without a doubt, DESTROYING vast wooded areas up here. Shade tolerant and very prolific, they easily move into wooded areas and set up shop. Once established they prevent EVERYTHING else from growing there. No more spring wildflowers, no more tree seedlings. Even maples, which are as a group very shade tolerant themselves, will not regenerate under the buckthorns. If you don't think something like this is a problem, it is because you lack the awareness of, and appreciation for, what was there before. Every exotic species is not invasive. I intend to plant some Norway spruce, for example, on land I plan to buy. Norway spruce can reproduce in this area, but will never become a problem plant. This discussion absolutely calls for a nuanced approach. Banning the use of ALL non-native species would be hugely ill-advised. But taking the view that any plant that can grow in a given locale should therefor be allowed to do so is just plain ignorant. The buckthorn invasion up here has been described as a slow-motion catastrophe, by people that can see and understand what's happening. Again, I think that people that don't see these invaders as problems have little understanding of the havoc they are causing. +oM

ZM, "if such a stimulus is applied to one part of a plant, might the response be exhibited in only a part of the plant" Very likely, sometimes. However, there is considerable evidence of remote signaling. So, a stress in one part of a plant can trigger a response in other parts. Percy Wright, a Canadian plant breeder, told a story of how "His uncle moved from Saskatchewan had moved west to the Okanagan and for sentimental reasons had grafted some ultra hardy Saskatchewan plums onto a few branches of the peach trees in his orchard. A harsh test winter arrived after a few years which decimated not only the peach crop, but also the trees themselves. Most were killed outright or at the least severely injured. However the peach trees with ultra hardy Saskatchewan plums grafted in the branches had no winter damage whatsoever!" The environmental stress (cold? short days?) was detected by the ultra hardy plums, which then communicated an appropriate response -- presumably to the roots. When they went dormant, the rest of the tree had no choice but to follow. Here's a more recent example of remote signaling: Plant Mol Biol. 2003 Nov; 53(4): 493-511. Rootstock effects on gene expression patterns in apple tree scions. Jensen PJ, Rytter J, Detwiler EA, Travis JW, McNellis TW "Like many fruit trees, apple trees (Malus pumila) do not reproduce true-to-type from seed. Desirable cultivars are clonally propagated by grafting onto rootstocks that can alter the characteristics of the scion. For example, the M.7 EMLA rootstock is semi-dwarfing and reduces the susceptibility of the scion to Erwinia amylovora, the causal agent of fire blight disease. In contrast, the M.9 T337 rootstock is dwarfing and does not alter fire blight susceptibility of the scion. This study represents a comprehensive comparison of gene expression patterns in scions of the 'Gala' apple cultivar grafted to either M.7 EMLA or M.9 T337. Expression was determined by cDNA-AFLP coupled with silver staining of the gels. Scions grafted to the M.9 T337 rootstock showed higher expression of a number of photosynthesis-related, transcription/translation-related, and cell division-related genes, while scions grafted to the M.7 EMLA rootstock showed increased stress-related gene expression. The observed differences in gene expression showed a remarkable correlation with physiological differences between the two graft combinations. The roles that the differentially expressed genes might play in tree stature, stress tolerance, photosynthetic activity, fire blight resistance, and other differences conferred by the two rootstocks are discussed." The stress (fire blight infection) affected the scion, but the rootstock somehow mediated the response. You're right that stress "can encompass a wide range of factors, many of which we might not think of as 'stress'." To paraphrase Forest Gump, "Stress is as stress does." In the broad sense, any sort of change in conditions is stressful. Many kinds of environmental stress are easily tolerated and usefully exploited by plants (or animals) long accustomed to them. However, unfamiliar changes/conditions can provoke more profound disturbances. Changes in photoperiod, for example, are often exploited by plants to provide a trigger for flowering. But when certain plants (e.g., tropical) are exposed to the wide ranging photoperiods of northern regions, they may respond oddly. In its native habitat (Brazil) the beautiful Amaryllis fulgida (Hippeastrum striatum var. fulgidum) bears a cluster of 2-4 flowers on a scape around 18 inches tall. But when the species was first cultivated in Britain in the early 19th century, it changed dramatically. "This specimen was imported by Mr. Harrison, from Brazil, and was drawn at Aighburgh, April, 1832. Some of the leaves measured twenty-nine inches in length and nearly three in breadth; the first flower-stem (bearing eight flowers) attained the height of thirty inches, and would probably have become somewhat taller, but was generously cut for the completion of the present figure; a second scape immediately succeeded it, twenty-eight inches high and having six flowers." By the end of the century, the gigantism was gone. Generations of offspring from the original specimens soon became adapted to the British seasons and reverted to the original "type." Other differences in "stress" are obvious. I was thinking of various species of roses that tolerate very different conditions, and are also stressed by very different conditions. Forest species (e.g., Rosa pinetorum) are weakened by exposure to full sun, whereas R. arkansana thrives in full light. R. rugosa happily tolerates salt spray when grown near the ocean, while others are likely to be killed. Some favor in humus (woodland types) while others grow and flower best in sand. Furthermore, there are distinct "sensitive periods" (or "critical periods") in plant development. An environmental condition that is usually tolerated without much difficulty can become very stressful during a fairly brief period of transition. And one more item that I just found while looking for something else: Biosystems. 1995 ;36 (1):71-7 8527698 Adaptive determinism during salt-adaptation in Sorghum bicolor. H Seligmann , G N Amzallag During adaptation to salinity, plants of Sorghum bicolor showed malformations affecting the leaves in development (DPL). At the end of the adaptation process, the plants were regrouped according to their pattern of DPL response. The distribution of the plant population in different patterns depended on environmental conditions. However, a positive relationship between the frequency of a pattern and its rate of development has been found. Similarly, a negative relation between the frequency of a pattern and the rate of senescence for the same pattern has been observed. The results reveal the existence of an orientation of the plant response towards the patterns with highest developmental rate and lowest rate of senescence. This property is defined as "adaptive determinism". Results indicate that the NaCl acts as a trigger for adaptation to a whole range of environmental perturbations. This suggests that adaptation to salinity is not a pre-programed response of the plants, and may be related to learning processes occurring in animals. Amzallag made some very interesting studies of the effects of salt on sorghum. I just decided to make a bibliography of his papers. Karl Here is a link that might be useful: Salt stress in Sorghum bicolor

Strange I didn't get any popup's guess my blocker was working. They truly are annoying. Sometimes I need to remind the popup blocker that it is on duty or at least should be. We are in the process of slowly removing most of the turf. I do my planning on paper, but that site has some other good stuff if you can get the pop ups to go away. I was just thinking that if I could draw it on the computer with plants I could see it after I decided what I wanted. If only I could figure out how to post photos and drawings here I could show you what areas we are working on. One area we are working on is a hill that is very steep. It is 8' wide and 42' long, on the north side of our house and no direct sunlight. We also are going to put in a few other areas. We have winter sown mostly natives. Although we will use non native ground covers on the hill as well. The one area I am having the hardest time visualizing is a fence with clematis. I took most everything other than the clematis out and am now working on what to put in that will complement the clematis and not get to tall so they don't get their needed sun. That garden area is curved and basicly 6' x 20'. The garden then curves around a corner and becomes a cottage garden style. It has full sun. Beyond those two we will expand existing gardens. We are on a corner lot so we have the boulevard to work on as well. Our lot is only 40' x 123', but very hard to work on it is all slope and hill. Errosion is a real problem so we have to do it slow and easy or the whole yard will end up in Minnehaha Creek. I think the best idea is to have the spring plant swap here and get suggestions from everyone that comes. Pauline

Jack, I can understand why an anonymous note would make you uncomfortable, and I can also understand why you don't want to name the plant because it's irrelevant to the discussion. However, if it is on your state's noxious list, should you as a responsible citizen continue to offer it for sale? If it is not on the list then there's no issue. Here's what I would do. Print out the "Severe Threat" list for your state from the Invasives.org website Vaccinium provided, post it in a prominent location and post below it your "Company Policy" that your customers will never find one of these plants for sale at your nursery. How many of your customers have actually ever seen that list? And, how many confuse "invasive" with "aggressive spreaders or seeders"? You'll be educating them. If a customer questions the invasiveness of a plant you sell, you can show them the list and explain the difference. I have never seen and never expect to see Japanese Honeysuckle, Kudzu, Tree of Heaven, Mimosa, Common Privet, or Chinese Privet for sale at any nursery in the South. However, I have purchased Variegated Porcelain Berry and have it growing on an arbor. That plant is not on my state's invasive list, but is on "Watch List B, plants that are severe problems in surrounding states, but have not been reported in Tennessee". I'll watch it. Interestingly enough on "Watch List A: Exotic plants that naturalize and may become a problem in the future", among others are listed Buddleia, Cosmos, Rose of Sharon, Spearmint, Peppermint, and Grape Hyacinth. All of these are commonly found in every nursery and most gardens. Where do you draw the line? Do you refuse to sell any plant that is listed on not only the Severe Threat List, but also the lower threat lists the watch lists? That's your decision and your conscience.