Every Wednesday, I hope to find a new ‘weed’ to investigate. My only criterion will be that I will not have deliberately planted the subject of our inquiry. Who knows what we will find…..

Duckweed (Lemna minor)

If you visit any still body of water at this time of year, you can be fairly sure to see a covering of tiny green plants. Sometimes, the whole of a pond or canal will be blanketed under the leaves, as if it were a bowling green – indeed, in the Second World War some people believed that this plant was grown on purpose to disguise the waterways. What we are looking at is Duckweed, one of the smallest flowering plants in the world, a prodigious multiplier and a great source of food for ducks (hence the name), and for pond fish.

Each group of leaves can split to form new plants…

The secret of Duckweed’s ability to cover whole ponds is down to its method of reproduction. Although it can produce flowers, it generally grows by division – each cluster of leaves can split into separate plants. This means that the plant can double its size in less than five days. One of the joys of the internet is that it allows anyone, whatever their passion, space to enthuse, and so, for a lovely little film illustrating how Duckweed grows, have a look at this from ‘The Charm of Duckweed’ site (click on the link to ‘Growth’ in the second sentence of the first paragraph).

Why does Duckweed sometimes grow so quickly? Well, it grows in ponds with high nutrient levels (particularly nitrates and phosphates). This gives me an indication that the falling leaves and other debris in my pond are starting to make the water a little too ‘rich’, and I should be a bit more meticulous about extracting them than I was last year. However, all is not lost – as Duckweed grows, it absorbs some of these nutrients, and so, provided I make sure that it is skimmed from the surface regularly, it’s actually a useful way of helping the pond water to become less of a stew. I always allow any plant matter that I remove to sit on the side of the pond for a few days, to allow the water creatures to return. After that, it’s excellent compost.

When Duckweed is removed from the water, it’s easy to see the long single roots that come from each cluster of leaves. It always reminds me a little of mustard and cress, and indeed it’s so full of fat and protein that it is grown for poultry and fish food.

One question that puzzles me a little is how Duckweed ended up in my pond. As I’ve mentioned before, it is a long way from any other bodies of water. However, when I was handling the weed I found it clung to my hands despite much vigorous shaking, and so it is likely that it will do the same to the legs of any birds who drop in to drink. It probably arrived in my pond wrapped around the ankles of a passing blackbird.

Although Duckweed is an annual plant, it is able to survive the winter quite comfortably. Once the temperature drops, the plant develops little starch-filled growths called ‘turions’ which fall to the bottom of the pond and spend the winter laying peacefully amongst the hibernating frogs and dragonfly larvae. In the spring, it floats back to the surface and recommences its reproduction. Once Duckweed has arrived in a pond, it’s very difficult to eradicate.

However, I am determined to love my Duckweed, regardless of its extravagant growth. For one thing, if it’s good enough for Shakespeare, it’s good enough for me:

‘The green mantle of the stagnant pool’ (King Lear, Act III Scene IV).

But the other reason is that, in previous years, I’ve spent a lot of time pulling blanket weed out of the pond. This is a thick, fibrous algae which wraps around everything, drowning insects and entangling tadpoles. This year, the Duckweed has shaded the pond to such an extent that I have no algae at all, and the water is much clearer. It’s much easier skimming off some little green leaves than pulling out great skeins of yellow-green slime. So, thank you Duckweed – as so often, a tiny, easily overlooked plant performs a big, meaty role in the ecosystem.

Every Wednesday, I hope to find a new ‘weed’ to investigate. My only criterion will be that I will not have deliberately planted the subject of our inquiry. Who knows what we will find…..

Pineappleweed (Matricaria discoidea)

I found this old friend growing by the side of the tarmac path in Cherry Tree Wood last week, and it brought back many memories of when I was a little girl. I grew up in Stratford, in East London, and our local park (the ‘Rec’) was full of Pineappleweed, growing up through the cracked surface of the playground and huddling along the pathways. I was entranced by the way that the crushed blooms smelled strongly of pineapple, and even today I couldn’t resist giving one or two of the flowers a little squeeze (just in the interests of research, you understand).

Pineappleweed is, in fact, a member of the daisy family , and is closely related to chamomile. If you take a good long sniff after making a cup of chamomile tea, there is a distinct pineappley scent, so this seems to be a family trait. Traditionally, Pineappleweed has been eaten in salads and used to treat uterine complaints (the family name, Matricaria comes from the Latin word for womb,  ‘Matrix’). Some people believe that the scent is closer to that of crushed apples, and the plant has the vernacular name of ‘Apple Virgin’,

As with so many of the ‘weeds’ we’ve investigated, Pineappleweed is not a native – it comes from north-eastern Asia and the western part of North America and ‘escaped’ from Kew Gardens in 1871. Since then, it has travelled to most parts of the UK, and the seeds are easily transported in the tyres of motorcars, which explains the many colonies of the plant in car parks and in the cracks of roads.

In North America, Pineappleweed was used by many Native American tribes. If you haven’t yet discovered it, can I recommend having a look at Plant Biographies by Sue C.Eland? Here is part of what she has to say about Pineappleweed:

“Babies in the Crow tribe could have a perfumed cradle as it was lined with the dried, crushed plant. The dried flower heads also provided a perfume for the Montana Indian and Blackfoot tribes, and they were an ingredient in a perfume mixture used by the Cheyenne.

Both the Kuskokwagmiut and Inuktitut Inuits enjoyed the scent in their steam baths, and Kutenai Indians,who used the dried leaves, also took pleasure from the scent and even made necklaces from the dried flower heads.”

We see, in this description, the way that a plant that is ignored and unnoticed in our urban environments has been used and enjoyed in a myriad ways by other communities.

Pineappleweed from Jan Kops ‘Flora Batava’

This humble little plant was one of the first to spark my interest in the natural world. I loved showing my friends how the plant not only looked like a pineapple, but smelled like one as well. This was enough to get me thinking about how plants are related to one another, and to start investigating the communities of animals that existed around these plants. Sometimes, a lifelong passion can be sparked from the smallest things.

Every Wednesday, I hope to find a new ‘weed’ to investigate. My only criterion will be that I will not have deliberately planted the subject of our inquiry. Who knows what we will find…..

Tufted Vetch (Vicia cracca) growing in St Pancras and Islington Cemetery

When I was doing my exploration of St Pancras and Islington Cemetery last week, I came across this delicate-looking, lilac-flowered plant. For all its seeming fragility, it was doing a great job of scrambling across the brambles and the bindweed. When looked at closely, it’s easy to see that this is a member of the pea family – the anchor-shaped hooks at the end of each frond of leaves are used to attach to whatever happens to be close by, and later in the year the plant will develop pods, each containing tiny ‘peas’.

A close look at Tufted Vetch makes clear that it is a type of pea….

Like all peas, Tufted Vetch fixes nitrogen in the soil. It does this because its roots contain nodules in which a bacteria called Rhizobia lives. While the plant is alive, the bacteria produces nitrogen compounds which help it to grow, and to compete with other plants. When the plant dies, the nitrogen is released, making it available to other plants and hence helping to fertilise the soil.  As nitrogen is one of the building blocks for DNA and for proteins, this is vital to the health of the whole ecosystem.

Tufted Vetch growing over bramble – © Copyright Lairich Rig and licensed for reuse under this Creative Commons Licence

Another name for Tufted Vetch is Cow Vetch, because it has been widely used as forage for cattle. Like all members of the pea family, it is also a great favourite with bees. The plant is native to Europe and Asia, but has been introduced to North America, where in areas of prairie it can be more vigorous than the native plants, crowding them out, and is therefore sometimes viewed as a detrimental weed. I find this a little surprising – although it is a scrambler, Tufted Vetch doesn’t seem much of a thug, certainly not when compared to plants like Bindweed.

The true beauty of Tufted Vetch is seen when it’s growing in a tangle with Birdsfoot Trefoil and Clover, bedstraws and buttercups. The gardener and cook Sarah Raven, in her book ‘Wild Flowers’, says that:

‘I often think I would love to cut one of these combinations with a single swipe of a sickle and put it all in a vase’.

I know what she means, but how much nicer lay on your back in a meadow, look at the tangle of flowers and watch the ladybirds and butterflies going about their business.

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Every Wednesday, I hope to find a new ‘weed’ to investigate. My only criterion will be that I will not have deliberately planted the subject of our inquiry. Who knows what we will find…..

Blackberries (Rubus fruticosus)

When I was growing up in East London, we would go blackberrying every year. We would jump into our Ford Popular and head for Loughton, where there were areas on the edge of Epping Forest that were head-high with brambles. We would take plastic  boxes and fill them to the brim with blackberries, which would be turned into pies and crumbles and jam. Sometimes, they would be mixed with apples, but often they’d be eaten on their own, heated with a little sugar and gobbled up with vanilla icecream.

In my remembrance, it was always hot, and although we’d get scratched it was worth it to savour those berries, slightly warmed from the sun. Juice would stain our hands and our clothes, but for a few hours we were getting food for free, just a couple of miles from where we lived. The berries always tasted better than anything that you could buy.

It was important to pick the right berries – only the fattest, blackest ones were ready to eat. The others were left so that other people could pick them when they were ripe. People took what they needed, and no more, and such was nature’s abundance that there always seemed to be enough. But it didn’t do to be tardy – the later berries were less juicy, more sour than the earlier fruit. Also, as the season moves on the fruit are more likely to be afflicted by mildew and other diseases which render them inedible. It was said that the devil pissed on the blackberries on Michaelmas Night (11th October), and so the season was, by then, effectively over.

Last week, I decided to notice blackberries in my walks around East Finchley, and was surprised by how many there were. There is a great stand dangling onto the High Road next the Amazing Grates fireplace shop, and indeed there is a spikey devil’s fishing-rod of bramble hanging over my back fence, bearing a dozen blackberries which I intend to eat before I cut the plant back.

A handful of brambles, far from ripe…

The thorns of the Bramble are particularly ferocious, but this is not surprising – the plant is a member of the rose family, and what is a rose without a thorn? You can see the family resemblance when the flowers are in bloom – those open-faced, blush-white blossoms are typical of the wild rose, and are always thronged with bumblebees and honeybees and all manner of other pollinators.

Bee on Bramble Flower Gwen and James Anderson [CC-BY-SA-2.0 (http://creativecommons.org/licenses/by-sa/2.0)], via Wikimedia Commons

We have been eating blackberries for a long time – the stomach contents of a neolithic man found in 1911 contained blackberry pips. In the past few decades, though, Londoners seem to have moved away from foraging, preferring to buy larger but distinctly inferior blackberries from Waitrose. So I was delighted to see a lady with the familiar plastic box full of blackberries walking through Coldfall Wood with her children last week. She looked at me a little sheepishly, as if afraid that I would berate her for picking the fruit, but instead I commended her good sense, and told her that I would be doing the same very shortly. What better way to notice the seasons, to get to know the neighbourhood ecology and to understand the true meaning of harvest than to pick some of your own food?