Jeremy Bartlett's LET IT GROW blog

The wonder of plants and fungi.

Sticky Nightshade, Solanum sisymbriifolium

Posted on 19 October, 2014 by Jeremy Bartlett19 October, 2014

Most of Norfolk’s arable fields are filled with a small and predictable set of crops: wheat, barley, sugar beet, potatoes and oilseed rape. Sometimes, however, a surprise awaits for the observant.

A few weeks ago my friend Sarah met up with some other friends for a walk at Stonebridge in Norfolk and noticed a strange crop growing in a large field by the side of the A1075. The plants had flowers like potatoes but the leaves were spiny and divided. She asked me if I knew what it was, and sent me a couple of photographs.

The mystery crop turned out to be Sticky Nightshade, Solanum sisymbriifolium. Around the same time I found the plant growing in Cambridge Botanic Garden and then last week Sarah drove me out to Stonebridge so I could take my own photographs.

A field of Solanum sisymbriifolium at Stonebridge in Norfolk.

Sticky Nightshade, Solanum sisymbriifolium is a native of South America: Brazil, Argentina, Uruguay and Paraguay. It is a member of the family Solanaceae and its white flowers (with a hint of purple or blue) are very similar to those of the potato (also a Solanum). Later in life, fruits form, which look like small, bright red tomatoes. These form inside a husk, like the tomatillo, Physalis philadelphica. The plant is an annual herb or small shrub and grows about a metre tall. Its stems and leaves are very prickly, with orange-brown spines. The leaves are sticky, and the fruits are slightly sticky too. The English name Sticky Nightshade is very appropriate.

Plants at Stonebridge, mid October

In Cambridge Botanic Gardens, late September

Sticky Nightshade’s leaves are divided and the name sisymbriifolium refers to their resemblance to the leaves of the mustard genus Sisymbrium. (The commonest British species of Sisymbrium is Hedge Mustard, Sisymbrium officinale.)

Other names for the plant include Fire-and-Ice plant, Litchi Tomato, Morelle de Balbis and Dense-Thorned Bitter Apple. (Morelle de Balbis is named after Giambattista Balbis, an Italian botanist from Turin.) The Global Invasive Species Database lists synonyms for the scientific name and names in various languages. The Rob’s Plants website has some great photos of the plant.

This plant often grows as a weed and is quite a problem in parts of South Africa, and in cattle pastures in South America. So why is this plant being grown at Stonebridge?

Potato Cyst Nematodes (PCN) are a damaging pest of potatoes, causing damage to the roots and reducing yields, often with no symptoms above ground, although in severe attacks plants can be stunted and have yellow leaves (chlorosis). Crop rotation and the use of partially resistant potato varieties can help to restrict the damage. (Read more on the DEFRA and Potato Council websites.)

Sticky Nightshade is grown as a trap crop for potato cyst nematodes. If Solanum sisymbriifolium is planted in a field infested with PCN, the nematode eggs hatch and the nematodes try to feed on the roots, but these are poisonous to the nematodes, which die. The nematode lifecycle is broken and an ordinary potato crop can be planted in the field. In the UK the plant is marketed as ‘DeCyst’ or ‘Foil-sis’ (reference).

(As an aside, research is also being carried out on the use of brassicas with high levels of glucosinolates to control potato cyst nematodes. When these crops, such as Indian mustard, are ploughed into the soil the glucosinolates break down into isothiocyanates, which are toxic to potato cyst nematodes.)

The fruit of Solanum sisymbriifolium is edible when ripe but apparently the taste isn’t great – You Grow Girl reckons the taste is insipid. The plant’s spines make picking a hazardous process.

Solanum sisymbriifolium contains the poisonous alkaloid solasodine. This can be used as a precursor to build other chemicals, such as steroidal compounds used in contraceptive pills. It may also be useful as an anticonvulsant.

Regardless of its various uses, there is no denying that Sticky Nightshade is a very pretty and fascinating plant in its own right.

Bristly Oxtongue, Helminthotheca echioides

Posted on 13 October, 2014 by Jeremy Bartlett13 October, 2014

In October many wild flowers have faded or gone to seed, but Bristly Oxtongue, Helminthotheca echioides (formerly Picris echioides) is usually flowering and I have become rather fond of it, after encountering it on autumn holidays and walks.

Bristly Oxtongue, Helminthotheca echioides

Bristly Oxtongue is a member of the Asteraceae, the daisy family, and its flowers are quite similar to dandelions, sowthistles and other relatives – a mass of yellow ray florets.

It is a bristly and pimply plant. It grows up to 90cm (three feet) tall and has branching stems with elliptical to oblong, wavy edged, pimply and bristly leaves. The lower leaves have winged stalks but the upper ones lack stalks and clasp the stem. The flowers are followed by a pappus of parachuting white seeds.

It grows in rough grassy places, on the edge of fields and by the seaside. In East Anglia it can be found by the River Blyth estuary at Southwold and on the edge of some arable fields in south Norfolk. It was very common in North Kent on a recent visit. It is well distributed in England and Wales, less so in Scotland and Ireland. In Northern Ireland it is declining and is a priority species. Like many agricultural weeds, Bristly Oxtongue is probably an archeophyte (a species introduced to the British Isles before 1500 AD). Its natural home is around the Mediterranean; it has also been introduced to parts of North America.

A mass of Bristly Oxtongue on the edge of a field in Kent.

Bristly Oxtongue is a very descriptive name for the plant. Flora Britannica also gives us Milton Keynes Weed (it is abundant there) and Richard Mabey’s book “Weeds” (Profile Books, 2012) gives us the local name of Langley-Beef. The latter was mentioned by agricultural improver William Ellis as a serious weed of peas. The name is a corruption of the French langue du boeuf (oxtongue) which incorporates the name of the Hertfordshire village of Kings Langley.

Names in other languages include the German Wurmsalat (worm salad), the Welsh tafod y llew gwrychog (lion bristletongue) and the Dutch dubbelkelk (double chalice).

The German name Wurmsalat and the scientific name Helminthotheca suggest that the plant could be used as an anthelmintic, to expel parasitic worms. The name echioides comes from the resemblance of the leaves to those of Viper’s Bugloss, Echium vulgare.

Young leaves of Bristly Oxtongue are edible, but the Plants For A Future (PFAF) website doesn’t encourage experimentation. The leaves are “Not wonderful raw … slightly better cooked. A rather bitter flavour.” I haven’t been tempted to try them. Fergus Drennan, however, says that the stems are amongst his favourites and describes them as “Mild, refreshing, solid, crunchy texture. Needs peeling.”

“Bristly Ox-tongue” is one of Alice Oswald’s wonderful poems in the book “Weeds and Wild Flowers” (Faber and Faber 2009), which is illustrated by equally lovely etchings by Jessica Greenman. I am obviously not the only person to be inspired by this pimply plant.

Common Earthball, Scleroderma citrinum

Posted on 12 October, 2014 by Jeremy Bartlett20 October, 2014

A couple of weeks ago I wrote about the Giant Puffball, Calvatia gigantea. It is one of several species of puffball that are good to eat, though all of them are smaller than the Giant Puffball.

But there is a common species of fungus that is superficially similar, which you shouldn’t eat – the Common Earthball, Scleroderma citrinum.

When I say superficially similar, I mean that both puffballs and the Common Earthball are spherical and sit on the ground without gills, pores or a stem. The Common Earthball is much wartier than any puffballs, with a thick and tough skin, covered with coarse and irregular scales. The skin is initially white, cream or yellow but may turn ochre-brown or green as it ages. (Citrinum refers to the citrine yellow colour of the skin.)

If you cut a mature Common Earthball open you will see the dark purply brown mass of spores inside; on really young specimens these are off-white, soon turning marbled brown and white. Puffballs have a pure white mass of spores when they are suitable to eat. You can squeeze a puffball like a marshmallow but the Common Earthball is much tougher and its skin will crack if you press hard enough (Scleroderma means ‘hard skin’). Sniff a Common Earthball and you may detect a slight unpleasant smell of gas; true puffballs smell pleasantly “mushroomy”.

Common Earthball

According to the Nature’s Secret Larder website, unscrupulous restaurants have been known to remove thin slices from the dark centre of Common Earthballs, soak them in truffle oil and serve them as real truffles.

This is a bad thing, as the Common Earthball is poisonous, although not in the league of the highly poisonous fungi such as Death Cap. If you eat it you are likely to experience gastrointestinal distress. (Wikipedia says that a few very sensitive individuals may experience lacrimation, rhinitis and rhinorrhea, and conjunctivitis from exposure to its spores.) In the United States the fungus is called the Pigskin Poison Puffball, a rather apt name.

Common Earthballs are indeed common and can be seen in autumn and early winter, in woodlands, on heathland, on shaded earth banks and on woodland and forest tracks. (The photographs above were taken in Blean Woods in Kent but I first saw the fungus many years ago at Buxton Heath, north of Norwich.)

Common Earthballs and puffballs have been lumped together in the gasteromycete fungi (the stomach fungi), but Common Earthballs are actually more closely related to boletes than puffballs, in particular boletes of the genus Gyroporus. If you want to know more, the First Nature website is a good place to start. It has some excellent photographs.