I need some help identifying this plant. I can only describe it as I don't have a camera. First of all, each year the plants die down, they propogate from seed which the white flowers 6"- 12" accross ( small white flowers grouped together to make a big one) The flowers are on a stalk that reaches approximately 6 - 8' in a very short period of time. The stalk is about 3-4" in diameter, is green whith a tinge of red and has white hairs lightly dispersed on it but especially where the stem of the leaves come off it. The leaves resemble that of rhubbarb only they are a lighter green and sharper. I have seen the really large rhubbarb looking prehistoric plant. That is not it. I have seen the plant at Queen Elizabeth park at the edge of a pond in the main grounds about 6 or 7 years ago. My husband and 7 year old son were taking the flowers off 3 days ago as we have figured out, if we don't the plants will over-run our yard. My son has had a violent allergic reaction where the plant contacted his skin. Blisters like I've never seen in my life. They are not getting smaller despite the prednisone the doctor prescribed for him yesterday at the clinic. I would like to take him to childrens' hospital but would like to be armed with a name and picture of the plant. I don't really want to take a sample of this meanie into a hospital where it may do more damage. Any help would be greatly appreciated.
Giant Hogweed (Heracleum mantegazzianum). The reaction is not allergic in nature but is a toxic reaction....The toxin makes the skin hypersensitive to UV light resulting in severe inflammation and blisters when subsequently exposed to sunlight (or tanning salon). Prednisone is still an appropriate treatment for the resulting inflammation but keep him out of the sun for good measure. Unlike poison ivy, one needs to actually come into contact with the sap to develop the reaction. I'm surprised your husband didn't break out as well. He either was more careful in not getting sap onto exposed skin or hasn't spend much time in the sun since the weekend. Wash all the clothes well! Wiki - Giant Hogweed
Thank-you so much for your expidited reply. Yup, that's it! My husband was also affected, though not as badly. The little helper was stuffing them into the bags. My son's blisters are so big, he can't bend his fingers. I wonder how long it will take for the prednisone to take effect. Again, thank-you very much for your help.
I wish I had known sooner what to do. Our doctor had no idea about the type of burns these were and he and the pharmasist are no doubt reading up furiously. We did spend the entire day inside yesterday, and I covered the blisters lightly with gauze. Luckily there is no pain. It's amazing how much power this plant has. The doctor lanced one of the blisters on his finger so he could move it. When I removed the bandage last night, the blister had reformed to it's original size...which is big...really big. No one has ever seen anything like it. I spent the day cursing the plant and then I thought about the unbelievable growth rate and hardiness of it. If one could isolate the growth "stuff" and "inject it" into trees for reforestation, could you imagine? A foot taller a day. A forest in no time...I thought of it..it's my idea! Just kidding - what a concept though. Does anyone know how long it will take for the blisters to heal? Is our whole summer shot? This is very depressing to us as it's a wonder when we get five days of consecutive sun here. My husband's burns have already turned purple. He wears pants at work shielding the burns from any light. I am concerned about the red marks on my son's cheek. He's not too keen on having his face wrapped. He had the same red marks on his left hand after we knew what caused the blisters on his right. The blisters are beginning to form on his left hand now after five days of the original exposure. No one seems to be able to give me any sort of time line for healing. Thanks again for all your help! This page has avoided a nervous breakdown.
The subsequent purple or brownish 'hyperpigmentation' can persist for several years. If it's on your son's face, best get a referral to a dermatologist fast and hopefully they can treat any hyperpigmentation. http://www.emedicine.com/emerg/topic446.htm
I got into some of this while working near a small river on Vancouver Island a few years ago. It left me with scaring that lasted for a few years. I broke out in blisters again a year later! The itching was terrible. Blistering appeared wherever this plants "sap" had rubbed on my skin. As mentioned here, the blistering happens because wherever the sap touches your skin it takes away your skins ability to filter out the suns ultra violate rays - you get a blistering sunburn along with the terrific itching. I ended up missing work (a WorkSafeBC injury claim) too. It's a nasty invasive plant. It looks nice enough but it's pretty dangerous as I found out.
The blistering was gone in about 3 weeks. The scars are still there. We'll make extra sure next summer that the areas are covered up. My son says he wasn't itchy. It sure did look terrible though. I received a couple more well deserved grey hairs. We'll be treating the plant area with a good herbicide in the spring.
The phyto-photodermatoxins of Giant Hogweed are psoralens or linear furanocoumarins. These chemicals are stored in the leaves, stems, roots, flowers and seeds – i.e. all sap bearing parts. The nasty reaction is called “phyto-photodermatitis” – which simply means “skin inflammation due to exposure to plant material and light”. In the case of the giant hog weed, the parts of the skin that was in contact with its sap becomes highly sensitive to light exposure. Photosensitisation can occur through either ingestion (e.g. cattle) or through direct contact with the skin. There are two types of damage. The immediate damage results in cell deaths, loss of tissue integrity, capillary leakage – therefore, the formation of bullae and blisters, and the onset of inflammation from the cell necrosis. The exact mechanism is still not entirely clear, but it is thought that these componunds react with ultraviolet light to produce radiant energy which oxidises essential amino acids in the skin, resulting in cell death. This is why, unlike other types of immediate contact allergic reaction, the symptoms are not seen or felt until several hours later. You need as little as 15 minute of sunlight exposure on the exposed parts to cause a toxic effect, especially on relatively unpigmented skin. Everybody is susceptible to these toxins - so, it is not an allergic reaction. However, certain groups have more severe skin reaction, especially children. The prolonged hyperpigmentation is an interesting phenomenon. It seems that the toxins interfere with the meloncytes’ DNA. Melanocytes are the pigment producing cells. The mechanism may be a form of photoinduced gene suppression. This leads to increased melanocyte production. More melanocyte=more pigments produced=darkened scars. Interestingly, the same mechanism involved in unleashing increased melanocyte production is the same that is involved in sunlight induced skin cancer – melanomas. However, so far, furanocoumarins do not seem to be a carcinogenic risk to human beings. But it does explain why the hyperpigmentation last for years - up to six years in fact. Other animals are not immune to poisoning. Ducks, for example, may get scarred deformed beaks. Cattles ingesting those weeds become photosensitised. While it is nasty to human beings, these compounds are highly beneficial protective mechanism for the hogweeds themselves – it’s their defense against herbivores of all sorts, that may have the intention of making a meal of these plants. In addition, these substances are known to be antifungals. Through the root system, they likely control the fungal population in the soil around them. Because of the delay in onset of skin lesions from the time of exposure, the acusative connection may be missed and the correct diagnosis not made.
Sheep and cattle, particularly dark-skinned breeds, can eat it safely if they adapt to it slowly as part of a mixed diet at first. They are used to control it by grazing - see pp.32-33 of the Giant Hogweed Best Practice Manual (pdf file): http://www.sl.kvl.dk/upload/kaempe_bjorneklo_eng.pdf
