Month: April 2012

Can you eat hogweed?

Grantham EcologyLeave a comment

Hogweed (Heracleum sphondylium) is a species which you can find almost everywhere – it thrives beside ditches, in hedgerow bottoms, in rough grassland, road verges, woodland. It is found, in fact, in many of the same habitats as nettle and, like common nettle, you can eat it! I will make it clear at this point that this refers to common hogweed rather than giant hogweed!

The description of hogweed taken from Rose’s Wildflower Key reads as follows:

“Robust, roughly hairy biannual to 200cm; stems hollow, ridged, with downward pointing hairs. Leaves 15-60cm, once pinnate, rough, grey-green, with clasping bases and with ovel- to oblong-lobed, pointed, coarse-toothed leaflets to 15cm long, lower ones stalked. Umbels (flower heads) 5-15cm, stalked, many rayed; bracts usually none, bristle-like, down-turned. Flowers white or pinkish, 5-10mm across; petals notched, unequal. Fruits long, oval, whiteish green, very flattened, smooth with club shaped dark marks on sides.”

Hogweed is a species which is fairly distinctive although a little care is required if you are not all that familiar with it. There are a number of other species in the carrot family which is could possibly be confused with but I have outlined below the key differences you need to look for.

1) Firstly, many other members of the carrot family have feathery or frilly leaves – think of cow parsley or even the tops of domestic carrots. Hogweed will never be thin and fine like these.

2) Never touch any member of the carrot family with red or purple spots on the stems – this will keep you clear of giant hogweed and hemlock which can be very toxic. It will also distinguish rough chervil whose leaves are much finer than the hogweed anyway.

3) Never eat any umbellifer which is hairless – again this should keep you away from hemlock!

4) Look in hedgerow bases and areas of rough grassland – these are favourite habitats. Species with similar leaves can be found on the coast amongst rocks and shingle such as Scot’s Lovage.

Hogweed
Hogweed leaf arising from grass and ruderal vegetation. The hogweed leaf is centre shot - ignore the nettles above it!

5) Wild celery isn’t a million miles away from hogweed, but is perfectly paletable so no worries there!

6) The leaves are pinnate – that is, leaflets are arranged on either side of the main stem. Each of these leaves is spikey and serrated. Avoid species whose leaves are twice pinnate – that is, they split again. This will keep you away from Wild Angelica which is also paletable so no worries! Sanicle and Astrantia are not pinnate – that is, there are not three separate leaves coming off the stem.

7) The plant should not be huge! Giant hogweed is very poisonous but, like its name suggests, it really is enormous. The only potential risk would be when the giant hogweed was just establishing and sending up the first shoots but a) you should still be able to tell that it will grow into something very large and b) always check for the red/purple spots on the stem, as described in point 4!

8) If in doubt, don’t bother. This is always a good rule to live by but, once you have your eye in, hogweed is a very characteristic species which you can easily identify. There are plenty of photos littered around the internet so use these to cross reference if you need to.

So, once you’re sure of your ID, you’re ready to harvest although do be careful, the stems can cause blisters (like nettles, not a problem once they are cooked!) so do wear gloves.

Hogweed leaf
Hogweed leaf ready for preparation

The best time to eat the leaves and stems is now, when the plant is young and fresh. Take the younger leaves and strip the leaves; the stalks can be cooked and eaten like asparagus and are particuarly nice if fried lightly with soy sauce and sesame seeds for addition to an oriental-style meal.

You can also eat the fresh leaves raw or cooked in a similar way to any other green leaf vegetable – there are recipe’s which substitute it for cabbage such as in Toad in the Hole.

A little later in the year, the buds can be picked and cooked – again, fried as part of an oriental-style meal can be delicious. When picking the buds though, always give due care to making sure that the leaves are indeed hogweed – and that the bud does come from the leaves you think they do! Cow parsley for example grows in the same habitats and you must make sure that the flowers aren’t crossing over.

Enjoy!

Wild Garlic

Grantham EcologyLeave a comment

Wild garlic or Ramsons (Allium ursinum) is a wild member of the lily family which you can generally detect from about 20 paces as the scent of garlic fills the air, especially in parts of the country where it can cover the woodland floor. The damper river valleys and hillsides in Yorkshire and Lancashire can have huge swathes and you can even find it growing along footpaths beside arable fields.

It is less frequent around Grantham and tends to be more restricted to typical woodland floor habitat – it can be found in Belvoir Woods to the west and there are some good colonies beneath the trees at Belton House.

Wild Garlic in Belvoir Woods
Wild Garlic growing in Belvoir Woods

At the moment, the leaves are full and fresh and the buds are just beginning to form – in a few weeks the white star-like flowers will appear too.

The garlic is not just restricted to the scent either – it can be used in cooking where it adds a mild garlicey flavour, more subtle than your average cloves. The leaves can be wilted down and used, or the bulbs can be chopped and cooked in a similar way as you might use normal garlic or spring onion bulbs. But although it is legal to take the leaves of wild garlic, it is illegal to uproot the plant (as you would have to do to get to the bulbs) without the landowners permission.

If you do find a good source of wild garlic, a delicious recipe which I found on another blog is a recipe for pesto. This uses nettle leaves as a base but I have made it using wild garlic leaves instead.

I have also cooked the leaves as part of a risotto – if you chop them down and stir them in, they make a wonderful accompaniment with asparagus tips.  This recipe on the Guardian website would make a good base!

It should be fairly easy to grow in your own garden too, if you have a good shady corner. The seeds can be bought from a range of places; the Naturescape wildflower farm at Langar is a good local option if you would like to establish your own colony.

Cowslip or Oxlip?

Grantham Ecology9 Comments

Cowslips are a common sight in April and May – brightening up grasslands and motorway verges with their swathes of nodding yellow flower heads. When I first started out in botany, I spent a good while convincing myself that the cowslips were indeed cowslips and not oxlips – Rose’s wildflower key tells you that cowslip is like oxlip but the ‘leaves are more wrinkled and the stem is more gradually tapered to the base’ which requires a certain amount of experience to compare! Luckily the sniff test (cowslip flowers smell like apricots) saw me right!

One simple rule of thumb is location  – true oxlips are a rare ancient woodland species restricted to the part of the country where the counties of Cambridgeshire, Suffolk and Essex meet. Unless you are in a location like this, you are unlikely to be encountering oxlip. But to be on the safe side, here’s a few more pointers!

Cowslip – Primula veris

IMG_9700
Cowslip flowers at Cribbs Meadow – the bright yellow bell-shaped flowers at the top of the stems all nod in a single direction

The flowers of cowslip, like those of oxlip, form a nodding head facing in a single direction. They can be long-stemmed – up to 25cm tall, but are often shorter where the nutrient levels are lower. The flowers are deep yellow with orange flecks in the centre.

IMG_8342.JPG
Cowslip flower at Muston Meadow showing the orange flecks within the flowers – these smell of apricot if you get in close!

You can find up to 30 flowers in a flower head, or sometimes just a few. Remember to take a sniff – the apricot aroma is quite distinctive in a fresh flower!

Oxlip – Primula elatior

IMG_2917.jpg
Oxlip flowering at Hayley Wood – the flowers nod in a single direction and there can be 10-30 in an umbel

Oxlip, as mentioned above, is a rare native found in ancient woodland in a restricted area of the country. If you are encountering the species on a roadside verge or in a meadow in Nottinghamshire, it’s probably not an oxlip. However the species can be bought as a plant, or grown from seed, so it is quite possible it can spring up in unexpected places if it escaped the confines of its sowing!

The oxlip is similar in structure and stature to the cowslip, in growing to ~25cm high and having 10-30 flowers on a head. As with the cowslip, all of the flowers will be nodding on the same side of the stem.

IMG_2865
The oxlip flowers are more open and spreading, lacking the bell-shape of the cowslip. They are generally a paler yellow, and lack the orange flecks inside.

The oxlip flower is less bell-shaped than the cowslip, with more open spreading petals and a lighter, paler yellow. The centres of the flowers lack the orange spots usually found with cowslip.

False oxlip – Primula vulgaris x veris 

IMG_8353
False oxlip along the Grantham Canal – the flowers have the orange flecks of the cowslip but spread wider, reflecting the primrose part-parantage of this hybrid. The flowers face in all directions, rather than nodding in a single aspect.

Just to add to the confusion, there is another species which can be confused with both cowslip and oxlip and this is the false oxlip. The latin name is Primula vulgaris x veris reflecting the fact that a false oxlip is in fact a cross between a primrose and a cowslip, occuring where these two species are found in close proximity. If you find something which you suspect to be an oxlip outside of the correct habitat and geographical area, a false oxlip is your most likely suspect!

The flowers are more open and spreading, a little like an oxlip, but you can see the telltale orange flecks which indicate the cowslip parantage. Rather than nodding in a single direction, as a pure oxlip or cowslip would do, these flowers face in all directions. There is significant variability in the character or these hybrids, with some being closer to the primrose parent and some more strongly representing cowslip.

The Hosepipe Ban – Should watering vegetables be excluded?

Grantham Ecology3 Comments

So once again, there is a hosepipe ban imposed across eastern and south-eastern England and Grantham is included.

The reasons for the ban are clear – if everybody takes care over their water usage now, the supplies we have will last longer, the rate at which we deplete them will decrease and the chances of more serious problems down the line will be reduced. It will also reduce pressure upon our reservoirs and waterways which will have clear ecological benefits. In summary, I am in favour of the ban.

However, it does appear short-sighted of the water companies to not exclude watering vegetables from this ban. It shows just how far we have become separated from our food and any form of self-sustainability that watering vegetables is considered a non-essential use of water, along with washing the car and hosing down the patio. Growing your own food should not be considered a luxury we can do without.

Technically, we can water with a watering can and therefore keep our own crops alive, but I know of many people who are not growing their own this year because the time and effort required to keep them alive without the use of a hosepipe are too great. This means, that more people will be buying their vegetables from the supermarket.

There was a study produced by the WWF in 2008 which looked at the water footprint of different countries and different crops. In the same year, a paper was published at waterfootprint.org which provides a table of average water footprints for a range of different produce. This takes into account, not only the quantities of water required for the industrial scale watering and growing of these crops but the water uses involved in processing, transportation and retail as well as accounting for pollution caused by nitrogen fertilisers and other harm to water supplies.

Taking a simple example, the average water footprint of 1kg of tomatoes is quoted as 180 litres of water.

Now logic dictates that removing all of the supply chain, haulage, processing, retail (including spraying vegetables with water to keep them fresh and other such activities) should reduce the water footprint of a home-grown tomato drastically. Even in terms of simple watering, your garden soils will hold a lot more water than arable fields where the soil structure is damaged from years of intensive agriculture.

So how much water would it use to grow tomatoes at home? A quick back of the envelope calculation from a few sources on the internet:

The average tomato plant produces around 2.5kg of tomatoes.

The water requirement of a tomato plant varies between 0.14 – 1.8 litres per day, depending upon the weather conditions. I am taking the figure of 1 litre per day as the average for ‘fairly sunny’ – ‘sunny’ weather as this will probably work out approximately correct across the average English summer. This is for the grown plant as well so it would be a conservative average as I am including the pre-flowering and pre-fruiting stages in the next step.

The average growing season, from the point at which the seedlings have developed to the point at which they are ready for harvest, is around 3 months, 90 days.

In theory therefore, a home grown tomato should be able to produce 2.5kg of fruit for 90l of water. If we scale the water footprint of commercially grown tomatoes up to the 2.5kg level, this is a huge 450l of water. A home grown crop of tomatoes should produce the same yield using one fifth, 20%, of the water required for a commercial crop of the same weight.

Whilst I accept that a few things may be missing from this calculation; you will probably wash your tomatoes when you bring them in, you may use a small amount of fertiliser etc., this is unlikely to make a big impact on the huge scale of the difference between these two figures.

Overall therefore, people should be encouraged to continue growing their own produce if we want to save on water use and deterring people from doing this seems short-sighted on the part of the water companies. I have framed this argument entirely in terms of water but there are of course multitude other advantages to growing your own – it cuts down on fertiliser, pesticides and carbon emissions as well as other greenhouse gasses and, of course, it tastes better.

Therefore, whilst I do support the hosepipe ban, I feel there is a strong argument that vegetables and other home produce should be excluded from this.