Looking Beyond The Water: Benefits Of Knowing The Environment
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The document discusses the benefits of understanding the natural environment, including identifying poisonous plants and avoiding toxicity. It mentions several poisonous species like giant hogweed and poison ivy that contain toxic compounds like furanocoumarins and urushiol. The document also lists interviews conducted with experienced paddlers about their knowledge of the outdoors.
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Looking Beyond The Water: Benefits Of Knowing The Environment
- 1. Looking Beyond The Water: Benefits Of Knowing The Environment
- 16. Oenanthe crocata
- 24. Urushiol
- 27. Source Wikipedia; photo by Etereve.
- 59. Same species…
- 79. Interviews with paddlers… • Ray Goodwin • James Raffan • Kevin Callan • Colin Skeath • Mark Kalch • Justine Curgenven
Editor's Notes
- . Blistering on the hand from contact with sap of Heracleum sosnowskyi combined with sunshine
- . Furanocoumarins are bioactive compounds that have phototoxic effects, that is they can have a photosensitising effect on the skin. The can also have mutagenic and carcinogenic effects. These chemicals bond with the DNA in epithelial cells in the skin, causing the skin to be unable to protect itself from sunlight. It is postulated that these chemicals are present in the plant to protect it from being eaten, particularly by co-evolved insect pests. Indeed research suggests many of these types of compound, especially cocktails of them, in members of the Apiaceae are indeed effective in keeping insect larvae pests at bay. Fuarnocoumarins occur in many members of the Apiaceae, not all of them included in this section. It also seems to be the case that plants can usually have low levels of phototoxicity but sometimes – due to environmental factors or perhaps time of year or a combination of both – sometimes they can have higher levels of phototoxicity. Hence the confusion about or variable accounts of the phototoxicity of plants such as cow parsley, Anthriscus sylvestris, wild angelica, Angelica sylvestris, as well as domesticated species such as parsnips, Pastinaca sativa and even the leaves of celery, Apium graveolens Furanocoumarins are present in all parts of the plants concerned, especially in the rhizomes and fruits. Photodermatitis from contact with the leaves or stem of the plants comes from the skin being wetted with the juice of the plant, typically after part of the plant is cut, crushed or broken off. It is then subsequent exposure to sunlight that causes serious damage to the skin {CLICK}
- . Here you can see redness and blistering on the skin of a leg that has come into contact with furanocoumarin containing plant juice and then been exposed to sunlight
- . This photograph taken in a damp valley bottom in East Sussex, UK. It illustrates how Giant hogweed plants can form a dense stand. This displaces many native and other non-native species. Clearly, this is not positive for local biodiversity, particularly for species of invertebrates that rely on native species {CLICK}
- . This glad is gradually being taken over by Giant Hogweed. In the middle distance you can see a dense stand of the plants at the far end of the open area. I cold only get so far along this glad before the density of the plants made it unwise for me to continue any further. All the plants in the distance were of a similar stature to the specimen I am standing near in the foreground of the photograph. And this plant has not finished growing yet. For reference, I am 6 foot tall. The stems can easily reach 5 metres, that’s 15 feet in height. As you can see here the leaves tend to be quite a light green, which seems quite yellowy. This puts it in immediate contrast with the other species of Heracleum we have looked at in this section, which tend to have mid to dark green leaves, sometimes seeming somewhat bluey=green. {CLICK}
- . This photo was taken in the lower reaches of the River Spey in Scotland in mid October. Along the banks in this area are many instances of Giant Hogweed plants… If we zoom in a little… {CLICK}
- . You can see the skeletal remains of the massive plants. Somewhat amusing is that they are in amongst a pretty solid mass of Japanese Knotweed, another invasive species, with which they seem to be competing here. Also in the middle of the photograph you can see that higher water levels have flattened the plants that were on the immediate foreshore. This is one way that the seeds are then dispersed downstream. {CLICK}
- . Here’s a close-up of a main stem with a side stem, Again note the clasping petiole and non-continuous, disrupted purple colouration. {CLICK}
- . Some young leaves spotted in rich grassland in a valley bottom near the Kent-Sussex border in the UK. There are at least 4 leaves here, possibly on two or more separate plants. To be honest, I didn’t root around to check and I didn’t have a stick to hand to poke them around with. But you can see the leaves here {CLICK THROUGH THE FOUR ARROWS} {CLICK}
- . So lets have a look a the plant. The plant is a perennial and quite distinctive… You’ll start to see the plant emerging quite early amongst the spring plants. This photo was taken in March in Cumbria in the nothwest of England. It’s a hairless herbaceous plant that looks quite fresh and inviting. Some aspects of the plant are reminiscent of celery, particularly the stout, crisp, unmottled stems. As you can see the plant is very happy, in or near shallow water. This is on the edge of a small stream in very damp ground. Generally this plant is most commonly found on the edges of streams, ponds and lakes, in marshes, ditches, dykes and other drainages along with shallow water and wet meadows. {CLICK}
- . Also taken in early Spring, this photo was taken in east Sussex in an area inhabited by alder and willow, and a slack stream surrounded by marshy ground. The yellow flowers you can see in the extreme bottom of the photo are marsh marigolds, Caltha palustris, which also enjoy this type of habitat. You can see the leaves are quite triangular overall. The lower, larger, leaves on the plant are typically 3-4 times pinnate {CLICK}
- . This photo is from a little later in the year, in early May in another part of Sussex, when the plants were generally more developed. This was taken from a wooden footbridge over a stream, which had along its margins a number of HWD plants. Again you can see the triangular shape of the leaf as well as the leaflets being suggestive of coriander or flat-leaved parsley, both of which are also members of the Apiaceae. If you look closely in the right hand third of the image, you can also see the umbels forming. The flower buds looking a yellowy-green. {CLICK}
- . And this is why the plant has the alternative common name of “dean man’s fingers”. The origin of the dead part should be fairly obvious and the cluster of finger-thickness tuberous roots give rise to the other part of the epithet. The suggestion of parsnips should be self evident too. To reiterate a couple of points made in the preceding slides, the tubers are reckoned to the the most poisonous part of the plant and apparently they taste quite pleasant and sweet. I hope, however, through looking at this distinctive plant in detail, you will be able to easily recognise it. OK, we’ll move onto another genus in the Apiaceae now. {CLICK}
- . Thames riverbank
- . This third and final example of a HWD umbel was photographed on the shore of Windermere, the largest natural freshwater lake in England. So, these plants are definitely not restricted to muddy ditches and little streams and ponds in the backwoods. This photo was captured in the second half of June. This example has more rays than the previous couple of examples. 12-40 rays is reckoned to be the range, although as few as 7 rays has been recorded. Note here you’ve also got some meadowsweet flowers on the left hand side of the HWD umbel. It’s not uncommon to find these plants growing near to each other where their ranges overlap. They both like similar conditions. {CLICK}
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- . Many plants have the ability to heal, not harm.
- . Thames riverbank
- . Thames riverbank