Weed of the Week Impatiens glandulifera Himalayan Balsam

Impatiens glandulifera Himalayan Balsam hymalayan balsaM flower 2 Himalayan Balsam, Impatiens glandulifera (also known as Indian Balsam, Jewelweed, kiss-me-on-the-mountain, Policeman’s Helmet) is a tall, herbaceous, annual flowering plant in the Balsaminaceae (balsam) family. The common names Policeman’s Helmet, Bobby Tops, Copper Tops, and Gnome’s Hat stand all originate from the flowers being decidedly hat-shaped. Himalayan Balsam and Kiss-me-on-the-mountain arise from the plant originating in the Himalayan mountains. It native range extends from the east Asia to the western Himalayas and south to Pakistan, it has, however, been naturalized in Britain and the USA. In its native habitat it is most typically found in shrubberies and bushy places and is often associated with grazing land.

STRUCTURE himalayan balsam leavesThe plant is an annual, classed as succulent and glabrous (smooth and hairless) and is very hardy. Impatiens glandulifera germinates in February to March. A period of chilling at 4º C for over 45 days is necessary to break seed dormacy. Germination is epigeal and occurs relatively early giving seedlings an advantage over other plants as long as they are not exposed to frost. After 12 days the first lateral roots emerge and by 18 days these roots, the radicle, and hypocotyl greatly elongate. Within four weeks the testa is lost and the cotyledons become photosynthetically active. The first true foliage emerges as a whorl of 4 leaves, with subsequent whorls of 3. Seed sets occur about 13 weeks after flowering (Beerling & Perrins, 1993; NWCB, 2007).Typically the plants grow between 1 and 2m tall with a soft green or red-tinged stem, and lanceolate leaves 5 to 23cm long. The leaf margins are sharply serrate with 20 teeth, or more, along each side. Each leaf has a stout petiole (stem), with small, glandular stalks found at the base of these petioles. When crushed, the leaves have a strong musty smell. The flowers develop between June and October and these are pink, with a distinctive hooded shape. They are typically about 3cm tall and 2cm broad and each plant develops several solitary flowers on an elongated axillary stalk.

hymalayan balsam flower

Individual plants reaching 2m in height, have translucent fleshy stems, pink-purple slipper-shaped flowers and large oval pointed leaves with obvious teeth around their edges. Each tooth carries a small globular ‘gland’ and produces large numbers of flowers which are followed by typically five chambered‘seed pods’ about 25mm long and 8mm broad.

hymalayan balsam seedpods

When mature and dry, the fruits split open explosively if touched, flinging the seeds a considerable distance (up to 7 metres) from the parent plant. After pollination (the flowers are very attractive to bees), the seed pods form. The seeds are small (2 to 4mm) and teardrop shaped. They range from very pale when immature through green to almost black when ripe.

hymalayan balsam seeds

The ripe seeds are light and float on water. When crushed the foliage emits a strong musky scent. Indeed, the name Impatiens (impatient) refers to this seed dispersal method. . The species name glandulifera comes from the Latin words glandis meaning ‘gland’, and ferre meaning ‘to bear’, in that the plant has glands that produce a sticky, sweet-smelling, and edible nectar. HISTORY IN THE UK In the UK the plant was first introduced in 1839 at the same time as Giant Hogweed and Japanese Knotweed. These plants were all promoted at the time as having the virtues of “herculean proportions” and “splendid invasiveness” which meant that ordinary people could buy them for the cost of a packet of seeds to rival the expensive orchids grown in the greenhouses of the rich. Within ten years, however, Himalayan balsam had escaped from the confines of cultivation and begun to spread along the river systems of England. Today it has spread across most of the UK and some local wildlife trusts organise “balsam bashing” events to help control the plant. However, a recent study (Hejda & Pyšek, 2006) concludes that in some circumstances, such efforts may cause more harm than good. They are now classed as an invasive species as their rapid growth and easy spread means that they easily out-compete native plants, particularly on disturbed ground, cleared ground and riverbanks. The small size of the seeds, the explosive nature of the seed pods and the buoyancy of the seeds means that they are easily distributed, particularly if growing by streams and riverbeds. The species is particularly frequent along the banks of watercourses, where it often forms continuous stands. It can also establish in damp woodland, flushes and mires. It is the tallest annual (species of plant that completes its life cycle in one year) in Britain and due to its rapid growth, it shades out most of our native species. Each plant produces about 2,500 seeds which fall to the ground, and with several parent plants close together, seeds can occur at a density of between 5000-6000 seeds per square metre.  Since the seeds float, watercourses are a prime route for dispersal of the species. Seeds can also begin to germinate in water on their way to new sites. Himalayan balsam has been identified as one of the highest risk (most unwanted) non-native invasive species in Britain. This is largely due to its impact on native waterside vegetation within designated sites.

PROBLEMS OF HIMALAYAN BALSAM

Since the species is rapidly expanding its range, a major concern is Himalayan balsam will dominate waterside vegetation and damp ground, at the expense of native species. There appears to be no direct detrimental impact on animal life. However, recent research suggests it competes for pollinators such as bumblebees with the native riverbank species, and so reduces seed set in these other plants.   If this species is growing in an adjacent site, or upstream of a site on a riverbank, then no matter how good on-site control is, re-colonisation is likely. The Balsam dies back from October onwards, exposing the now bare bank-sides to erosive winter flows and floods. Soil erosion from winter flows is damaging to spawning fish (lamprey and salmon). .An understanding of the wider area is necessary to determine if eradication or control efforts are likely to be successful. In some situations, eradication of all Himalayan balsam on site might not be possible due to the likelihood of re-colonisation. Work in partnership with neighbouring landowners to tackle Himalayan balsam . Himalayan Balsam is sometimes cultivated for its flowers. The aggressive seed dispersal, coupled with high nectar production which attracts pollinators, often allows the Himalayan Balsam to outcompete native plants.. Destroying riparian stands of Himalayan Balsam can open up the habitat for more aggressive invasive plants such as Japanese knotweed and aid in seed dispersal (by dropped seeds sticking to shoes). Riparian habitat is suboptimal for I. glandulifera, and spring or autumn flooding destroys seeds and plants. The research suggests that the optimal way to control the spread of riparian Himalayan Balsam is to decrease eutrophication, thereby permitting the better-adapted local vegetation that gets outgrown by the balsam on watercourses with high nutrient load to rebound naturally. They caution that these conclusions do probably not hold true for stands of the plant at forest edges and meadow habitats, where manual destruction is still the best approach. Himalayan balsam is known to reduce native plant diversity with some figures estimated a loss of about a third. This effect can be detected at both small and riverbank scales. It is possible to successfully control or eradicate Himalayan balsam from infested sites. However, while removal of Himalayan balsam increases plant diversity, the species that respond most dramatically are other non-native plants. Small infestations (most common in gardens) can easily be controlled by hand-pulling as the species is shallow rooted. Padded gloves should be worn to avoid risk of injury to hands. Seeds are not very robust and only survive for up to 18 months so a two year control programmes can be successful in eradicating this plant if there is not further infestation from upstream or adjacent sites.

CHEMICAL CONTROL OF HIMALAYAN BALSAM

Chemical control Himalayan balsam can be controlled by spraying the foliage with glyphosate. The plants should be sprayed in the spring before flowering but late enough to ensure that germinating seedlings have grown up sufficiently to be adequately covered by the spray. Glyphosate is sold under a number of brand names. Small infestations and individual plants can be controlled by using glyphosate in a weed wiper. This has the advantage of preserving native plants and grasses which would otherwise be killed by the glyphosate. The herbicide 2,4-D amine controls many broadleaved annual weeds and may also be used to control this species but is not recommended for use near watercourses. This selective herbicide will not kill grasses. It may be preferable to glyphosate in situations where the weed has not reduced complete cover of the grasses. A long-lance sprayer may assist in the spraying of less accessible areas out of the reach of conventional knapsack sprayers.

BIOLOGICAL CONTROL OF HIMALAYAN BALSAM

A rust fungus specific to Himalayan Balsam is to be released at locations in Berkshire, Cornwall and Middlesex as part of field trials to control the non-native, invasive weed Himalayan balsam (Impatiens glandulifera) using natural means. The release of the rust fungus comes after an eight-year research programme funded primarily by Defra and the Environment Agency, with contributions from Network Rail, the Scottish Government and Westcountry Rivers Trust. During the course of the research, testing in quarantine laboratories has established that the rust fungus causes significant damage to Himalayan balsam and does not impact on native species.

USES OF HIMALAYAN BALSAM

The green seed pods, seeds, young leaves and shoots are all edible.The young shoots and stems are edible, when cooked, but care should be taken as they contain high concentrations of calcium oxalate (which is broken down and leached out on cooking) but it is recommended that they are not consumed too frequently. Immature seed pods (before they reach the ‘explosive’ stage) are edible whole, and can be cooked like radish pods or mangetout (snow peas) and used in stir-fries and curries. The seeds themselves can be eaten raw and have a nutty taste that is variously described as being like hazelnuts or walnuts. The best way to collect the seeds is to enclose the seed pod in a bag and then pinch it off (this way, when the pods explode the seeds are not dispersed). Seeds can be toasted and ground to make flower, crushed and used as a spice or substituted in any recipe that calls for hazelnuts. They are excellent baked in cakes, breads and biscuits and make a welcome addition to stews and curries (a traditional use in Northern India). When collecting the seeds, you need not be too particular in removing all bits of the seed pods that you collect with them as the pods are edible. The seeds require a period of cold to activate from dormancy, as a result mature seeds (if carefully picked over) can be stored in an air-tight jar as a store-cupboard standby. They are useful for substituting in cakes instead of nuts for those with nut allergies and ground Himalayan balsam seeds can be substituted for ground almonds. The flowers can also be used to make floral jams and jellies.

USING HIMALAYAN BALSAM IN ORDER TO CONTROL IT

Himalayan Balsam at Bank Hall, Bretherton, Lancashire, England The Bionic Control of Invasive Weeds in Wiesbaden, Germany, is trying to establish a self-sufficient project to conserve their local biodiversity by developing several food products made from the Impatiens flowers. Eventually, if all goes well, this project will have the Himalayan Balsam financing its own eradication. “The Plant List: A Working List of All Plant Species”. Retrieved April 7, 2014. Jump up ^ Webb, D.A., Parnell, J. and Doogue, D. 1996. An Irish Flora. Dundalgan Press (W.Tempest) Ltd. Dundalk Scott, R. 2004. Wild Belfast on safari in the city. Blackstaff Press. ISBN 0 85640 762 3 Scannell, M.J.P. and Synnott, D.M. 1972. Census Catalogue of the Flora of Ireland. Dublin. Published by the Stationery Office. Hackney, P. (Ed)1992. Stewart & Corry’s Flora of the North-East of Ireland. The Institute of Irish Studies, The Queen’s University of Belfast. ISBN 0 85389 446 9 a b c Mabey, Richard; Produced by Susan Marling (Broadcast 25 July 2011), Mabey in the wild: Indian Balsam, A Just Radio Production, retrieved 24 July 2011 Check date values in: |date= (help) “Wanted!: Himalayan Balsam”. British Isles: A Natural History. The Open University. Retrieved 4 December 2009. “Alberta Invasive Plant Identification Guide”. Wheatland County, Alberta. 2012. Retrieved 9 June 2013. http://www.aka.fi/Tiedostot/Viksu/2012ty%C3%B6t/Sofia%20Mononen%20kilpailuty%C3%B6.pdf “Himalayan Balsam”. Royal Horticultural Society. Retrieved 2 June 2014. “Information Sheet 3: Himalayan Balsam”. Centre for Ecology and Hydrology: Centre for Aquatic Plant Management. Retrieved 2 June 2014. “Natural Resources Wales winning war against Ystwyth’s invader”. Natural Resources Wales. 2013. Retrieved 2 June 2014. • • http://www.celtnet.org.uk/recipes/ancient/wild-food-entry.php?term=Himalayan%20Balsam

Weed of the Week Aegopodium podagraria L. Ground Elder,

Aegopodium podagraria L. Ground Elder,
This plant has the reputation as one of the worst of garden weeds.  since it spreads in all directions extremely rapidly by means of its underground stems.

It is known by a variety of names amongst which ,Herb Gerard, Bishop’s weed, goutweed, and snow-in-the-mountain, and sometimes called English masterwort, and wild masterwort although other names, such as Farmers plague and jump about may be especially apt. Gound elder is a perennial plant in the carrot family (Apiacae)  that grows to a height of 100 cms in shady places. The name “ground elder” comes from the superficial similarity of its leaves and flowers to those of elder (Sambucus), which is unrelated. This species is native to Eurasia, and has been introduced around the world as an ornamental plant, where it occasionally poses an ecological threat as an invasive plant.

Structure

Goutweed, also known as bishop’s-weed and snow-on-the-mountain, is a herbaceous perennial plant. It is one of several species of Aegopodium, native to Europe and Asia. Most leaves are basal, with the leafstalk attached to an underground stem, or rhizome. The leaves are divided into three groups of three leaflets, making it “triternate.” The leaflets are toothed and sometimes irregularly lobed. Foliage of the “wild” type is medium green in color; a commonly planted variegated form has bluish-green leaves with creamy white edges. Sometimes reversion back to solid green or a mixture of solid green and the lighter variegated pattern occurs within a patch. The stems are erect, hollow and grooved. When crushed the foliage emits a characteristic odour which is at once pungent and aromatic. The two halves of the fruit are five angled and unlike most Umbelliferae, there are no oil ducts in the wall, this can be observed when the ripe fruit is cut across. the seedling leaves appear as unexpanded blades bent down against the leaf stalk and it is only the stimulus of light which causes the bent upper part of the leaf stalk to straighten when it has pushed its way through the screening leaf litter and soil.
ground elder leaves

Small, white, five-petaled flowers are produced in mid-summer. Flowers are arranged in flat-topped clusters (called compound umbels) and are held above the ground on a leafy stem up to about 3 feet tall. The seeds are small and elongate, similar in size and shape to carrot seeds, and ripen in late summer. although flowering freely seedlings are not often found. the plant tends to spread from vegetative growth of the underground rhizomes.  In contrast to the dense foliage cover produced by goutweed, flowering shoots are uncommon in densely shaded areas.
ground elder flowers
The rhizomes of goutweed are long, white, and branching, superficially resembling those of quackgrass (Elytrigia repens, also known as Agropyron repens). Patches of goutweed typically form a dense canopy and can exclude most other herbaceous vegetation.

Mabey relates that after digging up a herbaceous border removing all the rhizomes from the soil and from the roots of plants taken from the soil small shoots continued to emerge the following year.

“Here and there, near the edges of the bed, I found a few small leaflets unfolding. I carefully extricated the plants trying not to break the roots, to see what they had emerged from. Each seemed to have sprung from a small section of cut root thin enough to have been overlooked in the great cleansing. And the new shoots were growing not from nodes along the serpentine root fragments as in some species, but from a bulbous swelling at its tip.”
ground elder roots

History

No evidence of the presence of ground elder has been found in prehistoric excavations although it appears in Roman deposits. the Romans valued it as a medicinal herb for treating gout and as a vegetable. Mabey suggests that the plant was introduced by the Romans like the plants Alexanders and fennel, two other species introduced by the Romans that naturalised rapidly. It soon became naturalised and began to pick up folk names. The names goutweed and Bishop’s weed are references to the properties of the plant in alleviating that aliment.  Presumably Bishops were particularly prone to gout because of their high protein diet. Most peasants would not have had such a protein rich diet.  it was certainly widely cultivated as a pot herb. The first published record for ground elder is from Lyte’s herbal of 1578. Jack-Jump-About appears as a name in the sixteenth century. It was described rather ominously by Gerard in his herbal at the end of the sixteenth century in desperate tones.

“where it hath once taken roote it will hardly be gotten out againe, spoiling and getting every yeere more ground, to the annoying of better herbes”

This encroachment of ground elder is well recorded and refers to the ability of the plant to grow up to  3 feet underground in a single season. Consequently,  from one rosette an area of almost a square metre has been found colonised at the end of one year.

Invasive habit
Ground elder is an aggressive invasive plant that forms dense patches, displaces native species, and greatly reduces species diversity in the ground layer. Goutweed patches inhibit the establishment of conifers and other native tree species as well. Seed dispersal and seedling establishment is typically limited by shading, and new establishments from seed are restricted to disturbed areas. However, Aegopodium podagraria readily spreads over large areas of ground by underground rhizomes. The underground stems spread and branch below the surface usually at a depth of 1.5 to 2 inches. however Mabey reports that in a quarry in the 1990s a worker found roots of ground elder probing 30 feet below the surface.  In the angle between each scale leaf and the rhizome that bears it, there is an axillary bud that has the potential to develop into a new branch rhizome. At the end of the rhizome a leafy shoot emerges from the basal leaves from which axillary buds can grow to form rhizomes.Once established, the plants are highly competitive,  and can reduce the diversity of ground cover, preventing the establishment of tree and shrub seedlings. Because of its limited seed dispersal ability and seedling recruitment, the primary vector for dispersal to new areas are human plantings as an ornamental, medicinal or vegetable plant, as well as by accidentally spreading rhizomes by dumping of garden waste. It spreads rapidly under favorable growing conditions. Because of this it has been described as a nuisance species, and been labeled one of the “worst” garden weeds in perennial flower gardens.
ground elder roots seedling
A. podagraria has been introduced around the world, including in North America, Australia, New Zealand, and Japan, most commonly as an ornamental plant. It readily establishes and can become naturalized in boreal, moist-temperate, and moist-subtropical climates. It is an “aggressive” invader in the upper Great Lakes region and northeastern North America, Australia, Tasmania, and New Zealand Most colonies spread to neighboring natural areas from intentional plantings, or by the dumping of yard waste that includes discarded rhizomes. It can pose an ecological threat due to its invasive nature, with potential to crowd out native species. Because of its potential impacts on native communities and the difficulty of its control, it has been banned or restricted in some jurisdictions outside its native range, including in Connecticut, Massachusetts, and Vermont in the USA.
Control

Rhizomes developing new shoots
Once established, goutweed is difficult to eradicate. The smallest piece of rhizome left in the ground will quickly form a sturdy new plant. All-green goutweed may be more persistent and spread more rapidly than ornamental, variegated goutweed varieties, making the all-green type particularly difficult to control. However, all-green, forms are known to reappear from seeds of variegated varieties. Systemic herbicides such as glyphosate (Roundup®) that are translocated to the roots and kill the entire plant are most effective for goutweed control. However, glyphosate is non-specific and can damage or kill desirable native plants that are accidentally sprayed in the course of treating the goutweed. Contact herbicides are usually ineffective because goutweed readily leafs out again after defoliation. Personally, even after treatment with glyphosate I have found the plants regrow. This weed is by general agreement one of the most difficult to eradicate, except by laborious hand weeding.
Manual
Small patches of goutweed can be eliminated by careful and persistent hand-pulling or digging up of entire plants along with underground stems (rhizomes). Pulled plants can be piled up and allowed to dry for a few days before bagging and disposing of them. Be careful to pick up all rhizomes which, if left can re-root and sprout new plants. For large patches, a team of volunteers or use of herbicide is recommended. the rhizomes penetrate not only the soil but the root system of any plants growing in that soil. therefore in order to eliminate the ground elder, it is necessary to separate any rhizomes from within the root systems of plants growing in the borders, a laborious and tiresome procedure. Any small pieces of rhizome that break off can regrow and any fragments of rhizome left in the root systems of other plats can regrow.
Mechanical
Where appropriate, frequent short mowing may control or slow the spread of goutweed in lawns, along roadsides, and other areas.
Physical
Preventing goutweed from photosynthesizing in early spring (at the time of leaf-out) can control the plant by depleting its carbohydrate reserves. This can be accomplished by covering the patch with black plastic sheeting when the leaves start to emerge from the ground in the spring, and leaving it in place through the summer. A more effective option is to cut all plants once they’ve fully leafed out, using a mower, scythe, or weed-whacker type machine, and then cover the area with plastic. Covering the plants in mid- or late summer, after they have regained substantial starch reserves, is probably much less effective.
Integrative management strategies that combine herbicide with landscape cloth, bark mulch, and hand weeding to control goutweed in a garden are largely unsuccessful because sprouting occurs from either rhizomes or root fragments left in the soil Hand pulling, raking, and digging followed by monitoring to control goutweed may be effective; however, caution must be taken to remove the entire rhizome and root system. Removing flowers before seed set may help control the spread of goutweed.] Because goutweed’s starch reserves are typically depleted by spring, removal of leaves in spring could be effective in starving the plant. Once goutweed has been removed, the patch should be carefully monitored periodically for a few years. New shoots should be dug up and destroyed. Revegetation with other plant materials is recommended.
The most effective means of control is to prevent its establishment in natural communities. It is thus recommended to plant goutweed only on sites not adjacent to wildlands and in gardens where root spread can be restricted.
Ornamental use
A variegated form is grown as an ornamental plant though with the advice to keep it isolated.
Importance to wildlife
It is used as a food plant by the larvae of some species of Lepidoptera, including dot moth, grey dagger and grey pug, although A. podagraria is not the exclusive host to any of these species.
Dot Moth
dot moth

Grey Dagger
grey dagger moth

Grey Pug
grey pug

Stem profile – no toxic look-alike has a triangular profile.
Uses as food and medicine
The plant is said to have been introduced into England by the Romans as a food plant. The tender leaves have been used in antiquity and throughout the Middle Ages as a spring vegetable, similar to spinach. It was called Bishopsweed and Bishopswort, because so frequently found near old ecclesiastical ruins. It is said to have been introduced by the monks of the Middle Ages, who cultivated it as a herb of healing. It was called Herb Gerard, because it was dedicated to St. Gerard, who was formerly invoked to cure the gout, against which the herb was chiefly employed. Descriptions of its use are found among monastic writings, such as in Physica by Hildegard von Bingen. Gerard tells us that:
‘with his roots stamped and laid upon members that are troubled or vexed with gout, swageth the paine, and taketh away the swelling and inflammation thereof, which occasioned the Germans to give it the name of Podagraria, because of his virtues in curing the gout.’

Young leaves are preferred as a pot herb. It is best picked from when it appears (as early as February in the UK) to just before it flowers (May to June). If it is picked after this point, it takes on a pungent taste and has a laxative effect. However, it can be stopped from flowering by pinching out the flowers, ensuring the plant remains edible if used more sparingly as a pot herb.
It also had a history as a medicinal herb to treat gout and atthritis] applied in hot wraps externally upon boiling both leaves and roots together. The generic name is a corruption of the Greek aix, aigos (a goat) and pous, podos (a foot), from some fancied resemblance in the shape of the leaves to the foot of a goat. The specific name is derived from the Latin word for gout, podagra, because it was at one time a specific for gout.
Ingested, the leaves have a diuretic effect and act as a mild sedative. Its use as a medicinal herb has largely declined during the modern era.

1. “The Plant List: A Working List of All Plant Species”. Retrieved 5 December 2014.
2.  a b Goutweed (Aegopodium podagraria) Mrs. Grieve’s “A Modern Herbal” at Botanical.com]
3.  a b “Plant Conservation Alliance, Alien Plant Working Group: Goutweed”.
4. Webb, D.A., Parnell, J. and Doogue, D. 1996. An Irish Flora. Dundalgan Press Ltd, Dundalk. ISBN 0-85221-131-7
5.  a b Agronomy Division (1969). “Ground elder (Aegopodium podagraria)”. Tasmanian Journal of Agriculture 40 (30): 190.
6.  a b Dawson, F. Hugh; Holland, David. (1999). “The distribution in bankside habitats of three alien invasive plants in the U.K. in relation to the development of control strategies.”. Hydrobiologia 15: 193–201. doi:10.1007/978-94-017-0922-4_27.
7. ^ “US Forest Service, Aegopodium podagraria”.
8. “The USDA PLANTS Database. National Plant Data Center, Natural Resources Conservation Service, United States Department of Agriculture. Baton Rouge, LA.”.
9. Clark, Frances H.; Mittrick, Chris; Shonbrun, Sarah. (1998). “Rogues gallery: New England’s notable invasives.”. Conservation Notes of the New England Wild Flower Society 2 (3): 19–26.
10.   Czarapata, Elizabeth J. (2005). Invasive plants of the Upper Midwest: An illustrated guide to their identification and control. pp. 215 p.
  “Ground Elder – Bishops Weed (Aegopodium podagraria)”. Edible Plants. 2009. Retrieved 2010-02-15.

12. Richard Mabey Weeds 2010 Profile books London

13. Sir Edward Salisbury Weeds and Aliens  The New Naturalist Collins London 1961