Common Bird’s-nest Fungus, Crucibulum laeve

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Common Bird's-nest Fungus, Crucibulum laeve

Common Bird’s-nest Fungus, Crucibulum laeve, growing in our greenhouse.

A week ago I cleared the last tomato plants out of our greenhouse in the back garden and brought the last green tomatoes indoors to ripen (note 1). As I pulled up the tomato plants, I had a lovely surprise: a little cluster of bird’s-nest fungi on the soil.

Bird’s-nest fungi have fruiting bodies that resemble tiny birds’ nests, complete with eggs. The fungi feed on decaying organic matter and can be found on soils containing plant debris such as little twigs, on wood chip and bark mulch, or growing on decaying wood.

Bird’s-nest fungi are members of the family Nidulariaceae (nidulus means small nest), part of the order Agaricales, which includes familiar species of fungi such as cultivated mushrooms (Agaricus bisporus) and  well-known wild species such as Shaggy Inkcap (Coprinus comatus, which I have already written about) and Fly Agaric (Amanita muscaria).

Worldwide, there are five genera of fungi in the Nidulariaceae: Crucibulum, Cyathus, Nidularia, Mycocalia, and Nidula (note 2).

The species I found in the greenhouse was the Common Bird’s-nest Fungus, Crucibulum laeve, one of the most common species. It can usually be found growing in small clusters in late autumn and winter. (I counted nine fruit bodies, growing singly or in small groups.)

Common Bird’s Nest fungi are found through much of the British Isles and in mainland Europe and Asia, as well other temperate areas, including many parts of North America. They are probably overlooked due to their small size and the way they blend with their background – I like to think I am observant, but it didn’t spot them until I’d nearly finished work in the greenhouse.

To start with, the fungus’ cups are covered in a fragile yellowish membrane, known as the epiphragm. This soon breaks apart as the fruit body expands to form the “nest” –  a cup that contains a number of small white “eggs” (note 3). These are actually spore packets, known as peridioles. Each peridiole is attached to the the cup wall by a thread known as a funiculus.

Common Bird's-nest Fungus, Crucibulum laeve

Three young specimens of Common Bird’s-nest Fungus, Crucibulum laeve. In the lower two the epiphragm is just starting to break.

The peridioles of bird’s-nest fungi are spread by the splashing of raindrops, which fall into the cup and send them flying. The attached funiculus helps the periodiole on its journey and when it lands may coil around a grass stem, preventing further flight. Ideally a passing grazing animal will then eat the grass and the periodiole will pass through the animal’s body unharmed and arrive in a new location in a parcel of nutritious dung. In the greenhouse any water drops will come from my watering can and there aren’t any grazing animals (unless you count slugs, snails or woodlice) but the fungi should disperse their spores just fine (note 4).

Other types of bird’s-nest fungi you may find in Britain include the following:

This autumn I’ve also seen Field Bird’s-nest and Fluted Bird’s-nest in Norwich, but I have never encountered Dung Bird’s-nest or Pea-shaped Bird’s-nest.

Field Bird's-nest, Cyathus olla

Field Bird’s-nest, Cyathus olla

Fluted Bird's-nest, Cyathus striatus

Fluted Bird’s-nest, Cyathus striatus. Taken in low light conditions, this is not the best of pictures, but the fluting inside the cup makes the fungus easily recognisable.

Notes

Note 1 – If any tomatoes are stubborn to ripen I will put them in a paper bag or shoe box with a banana. This will eventually sacrifice the banana, but the ethylene gas it gives off will help to ripen the tomatoes.

Note 2 – In Britain, you are most likely to encounter members of the first three genera, although the NBN Atlas lists 144 records for Mycocalia denudata at the time of writing. It is a tiny member of the family. In Germany it has been recorded from decaying plant remains and also on rabbit and sheep dung. In New Brunswick (Canada) it has been recorded on lemming dung. There are photographs of Mycocalia denudata on both these websites.

There are five species of Nidula worldwide, which can be found in North America, Japan, the Himalayas and parts of the Caribbean, but not in Britain.

Note 3 – The First Nature website says that the cup contains 5 – 10 “eggs” (peridioles) but Geoffrey Kibby, in his book “Mushrooms and Toadstools of Britain and Europe, Volume 1” (2017)  says that the number ranges from 10 – 15, with sometimes as many as 20 per cup. Sterry and Hughes say 10 -15. I counted eleven “eggs” in one of my smaller specimens.

Kibby gives Crucibulum laeve the more descriptive English name of White-egg Bird’s-nest; Common Bird’s-nest is used more generally, including in Sterry and Hughes in “Collins Complete Guide to British Mushrooms and Toadstools” (2009).

Crucibulum means crucible and laeve means smooth.

Note 4 – The New Brunswick Museum web page on Bird’s-nest Fungi cites some fascinating work that was done on artificial bird’s-nest fungi, described in Harold Brodie’s book “The Bird’s Nest Fungi” (University of Toronto Press, 1975). Brodie and Buller found that the angle of the cup walls is critical to the distance the peridioles can travel. “Too great or too little an angle and they will not travel as far. The ideal angle for dispersal by large raindrops having a terminal velocity of 4-8 meters per second is between 60 and 70 degrees with the horizontal.”

Szechuan Pepper, Zanthoxylum simulans

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Szechuan Pepper, Zanthoxylum simulans

Szechuan Pepper, Zanthoxylum simulans

Our Szechuan Pepper bush, Zanthoxylum simulans, is producing fruit for the first time.

I first read about Szechuan Pepper ten years ago, when I bought Mark Diacono’s book “A Taste Of The Unexpected”  (note 1). I wasn’t able to source a plant for Grapes Hill Community Garden in 2011 but when we replaced the big raised bed in our front garden in autumn 2016 I had another look online and bought a small plant from Jurassic Plants. It had clearly been grown with love and care, and came with an A4 printed sheet of care instructions. I kept it in an unheated greenhouse and planted it out in early spring 2017. (In the UK, plants are available from other sources too, such as Burncoose Nurseries and Pennard Plants. Seeds are available from Chiltern Seeds.)

Two years later, the Szechuan Pepper is doing well and has reached about four feet (1.2 metres) high, with a similar spread. Without pruning, it could ultimately reach seven metres (23 feet) tall but I will intervene long before that – and, if space is really limited, it is apparently a good bonsai plant (note 2). It is very hardy and seems tolerant of drought and likes the sunny, south-facing spot where it is growing. (It will also grow in light dappled shade.)

Zanthoxylum simulans is a member of family Rutaceae, the Citrus family, along with well-known fruits such as Oranges, Lemons and Grapefruit. There are about 250 species of Zanthoxylum worldwide, trees or shrubs native to warm temperate and subtropical areas. Zanthoxylum simulans is native to eastern China and Taiwan. The genus Zanthoxylum is so-called because some species have yellow heartwood (Ancient Greek xanthos (yellow) and xylon (wood)).

So why am I growing Zanthoxylum simulans?

It is an interesting and quite attractive plant, with rather formidable spines on its stems and ash-like leaves, which turn an attractive reddish-yellow in autumn. The shape of the leaves gives the plant its alternative English names of Prickly Ash, Chinese Prickly-ash and Flatspine Prickly-ash.

The flowers appear in spring and are rather tiny – I missed them altogether this year but they are described as tiny, cup-shaped flowers in cymes 5 cm (2 inches) across. (Mark Diacono says that they resemble small elderflower florets.) By July or August the plant has clusters of small pinky-red fruits. These are ornamental, but also contain the plant’s finest and strangest secret.

Known as Szechuan peppercorns, each berry is about the size of a black peppercorn (an unrelated, tropical vine, Piper nigrum). The seed is black and is revealed when the berry splits open in the autumn. The seed itself is tasteless but its pink coating (the pericarp) gives a fizzing and numbing sensation in the mouth and on the tongue.

Szechuan (Sichuan) peppercorns are used to make Chinese five spice powder, along with star anise, fennel, clove, and cinnamon. The powder is readily available, but Mark Diacono gives a recipe for making your own in his book and 2010 Guardian article. The Spruce Eats website lists a number of recipes using the powder (including Bang Bang Chicken, Dan Dan Noodles and Szechuan Beef) and Mark Diacono suggests Five Spice Pork Rillettes. The Vegetarian Times website lists several vegetarian and vegan recipes that use five spice mix, such as Garlic Ginger Vegetable Stir-fry and Spicy Peanut Noodles. Other culinary uses include flavoured salt or as additives in beer or in flavoured oils.

The experience of tasting a Szechuan Pepper is described by Mark Diacono as “like all peppers… much more an experience than a flavour”. He separates out two contrasting elements of flavour: “ma” and “la”. First comes “ma”, a numbing pungency that sets the tongue and lips tingling, followed by “la”, a spicy heat, which is (slightly) similar to the heat from a chilli. In my own experience, the “ma” is much more obvious. It doesn’t last long, but it is strangely addictive. I often pick a single berry when I walk to the allotment, carefully suck the pericarp and discard the seed. Full fizzing numbness starts several yards down the road, but has worn off after two or three minutes.

The ingredient in Szechuan Pepper that causes the tingling numbness is the compound hydroxy-alpha-sanshool. Rather like the capsaicin in chillies, the chemical interacts with nerve cell receptors in the lips and mouth. In his book “On Food And Cooking: The Science And Lore Of The Kitchen“, the American author Harold McGee describes the chemical’s effects in the mouth:  “they produce a strange, tingling, buzzing, numbing sensation that is something like the effect of carbonated drinks or of a mild electric current (touching the terminals of a nine-volt battery to the tongue). Sanshools appear to act on several different kinds of nerve endings at once, induce sensitivity to touch and cold in nerves that are ordinarily nonsensitive, and so perhaps cause a kind of general neurological confusion.” (note 3).

The import of Szechuan peppercorns into the United States was banned in 1968 (along with all other citrus products) because Zanthoxylum plants act as hosts for a type of canker that attacks citrus trees. However, the ban was lifted in 2005 for peppercorns that had been heat-treated to kill off any potential pathogens, much to the relief of Chinese communities in particular.

My single Szechuan Pepper has set plenty of fruit by itself, but even more fruit can be set if you have more than one plant.

If you can’t get hold of Zanthoxylum simulans, Mark Diacono suggests Zanthoxylum schinifolium. (“I prefer its lighter touch – it’s more “ma” than “la”.“) UK suppliers include Van Den Berk Nurseries (who have some good photos and information on their website) and (for seeds) the Agroforestry Research Trust.

The wonderful Chelsea Physic Garden in London has a big specimen of the related North American species, the Toothache Tree (aka Common Prickly-ash)  Zanthoxylum americanum, “with spines and knobs along its trunk and branches – the small, round, fleshy fruits smell strongly of cloves when crushed“.

It is also worth rubbing the leaves of a Szechuan Pepper plant to release a heady hit of spice and citrus. In the words of Mark Diacono once more: “Like a tea break, it provides a perfect punctuation to the day, and is up there with popping fresh peas into your mouth as one of the finest kitchen-garden treats.”

Notes

Note 1 – Mark Diacono, “A taste of the unexpected : growing your own remarkable fruit, vegetables, nuts, herbs, spices and flowers”, Quadrille Publishing 2010.

The book appears to be out of print, but you may be able to buy a secondhand copy or borrow it from a library.

Mark also wrote about Szechuan Pepper in a 2010 article in The Guardian, “How to grow Szechuan pepper and make Chinese five spice“.

Note 2 – Many Zanthoxylum species make excellent bonsai specimens and can be grown successfully indoors in temperate climates. According to Wikipedia, Zanthoxylum beecheyanum and Zanthoxylum piperitum are two species commonly grown as bonsai.

Note 3 – A revised second edition of the book (published by Hodder & Stoughton in 2004)  was reviewed in The Guardian in 2004 by Tom Jaine.

Nodding Bur-Marigold, Bidens cernua

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Nodding Bur-Marigold, Bidens cernua

Nodding Bur-Marigold, Bidens cernua. Rayed form (var. radiata), 2nd September 2019.

At the beginning of September Carl, my older brother-in-law, told me about an interesting plant he had seen at Whitlingham Country Park, on the outskirts of Norwich. It was the rayed form of Nodding Bur-Marigold, Bidens cernua (var. radiata), a plant I hadn’t seen, so the next day I cycled out to take a look. I found the plants very easily, just off the path on the southern edge of the Great Broad (a former gravel pit).

Nodding Bur-Marigold, Bidens cernua, is a member of the Asteraceae, the Daisy family, and I have already written about some other members of the family on this blog, including Oxeye Daisy, Pineapple Weed, Gallant Soldier, Dandelion, Mexican Fleabane, and Bristly Oxtongue. The Asteraceae is probably the largest family of flowering plants, with more than 32,000 species worldwide (note 1).

Members of the Asteraceae have composite flowers – what appears to be a single flower is actually a composite flowerhead known as a capitulum (note 2). Taking just three examples:

  • Dandelion flowerheads are made up only of ray florets.
  • Thistle and cornflower flowerheads are made up of only disc florets.
  • Flowerheads of the Oxeye Daisy consist of an inner cluster of yellow disc florets, surrounded by a ring of white ray florets which look like petals.

The rayed form of Nodding Bur-Marigold (var. radiata) has flowers structured rather like an Oxeye Daisy. The inner disc florets are a dull yellow, and these are surrounded by a ring of bright yellow, petal-like ray florets. But this very attractive form of Nodding Bur-Marigold is not particularly common and you are far more likely to see plants that only have disc florets. Both forms were growing by Whitlingham Great Broad.

In contrast to the rayed form of Nodding Bur-Marigold, the rayless form of the plant is not very spectacular, and it blends into its surroundings. However, both forms of the plant have characteristic undivided leaves with saw-tooth edges.

Nodding Bur-Marigold, Bidens cernua

Nodding Bur-Marigold, Bidens cernua. (Rayless form.) 2nd September 2019.

Bidens cernua is an annual, and when I visited the site again later in September the plants were already running to seed and many were developing mildew and looking past their best.

Nodding Bur-Marigold grows in damp places, such as on the margins of slow-flowing rivers and streams, in ditches and marshes and by broads, ponds and meres. The sites where it grows are often places subject to flooding in winter. It is widely distributed in the British Isles, particularly in England, Wales and Ireland. However, it is declining in the south-east of England as its habitats are destroyed. It is also found through many temperate parts of Europe, Asia and North America. There are good pictures of the plant on the Wild Flower Finder (rayless form only) and Illinois Wildflowers websites. (The latter lists some of the insects that are attracted to the plant in the United States.)

Bidens cernua contains the compound Phenylheptatriyne (PHT). This chemical, a type of polyacetylene, is phototoxic to bacteria and also acts as a fungicide. PHT may also have allelopathic properties: it appears to inhibit the growth of seedlings from other plants. Quantities of the chemical in Bidens cernua vary throughout the year, reaching their highest levels in October.

The closely related Trifid Bur-Marigold (Bidens tripartita) was growing alongside (and amongst) the Nodding Bur-Marigold at Whitlingham. Its flowers were similar to the rayless form of Bidens cernua but the leaves were distinctively divided into threes – hence trifid (but not triffid) (note 3). Although Trifid Bur-Marigold grows in similar areas to Nodding Bur-Marigold, it prefers slightly drier ground. It is also an annual. The leaves can be eaten when cooked and the plant has various possible uses in herbal medicine and was used medicinally to used to staunch blood flow.

Trifid Bur-Marigold, Bidens tripartita

Trifid Bur-Marigold, Bidens tripartita, growing next to Nodding Bur-Marigold at Whitlingham Great Broad (22nd September 2019).

The teeth on Bur-Marigold seeds attach to passing animals, including plant photographers and canoeists, and this aids the plant’s spread. This is known as zoochorous seed dispersal. (The Wild Flower Finder website has some good pictures of the seeds.) They also give the plant its generic name: Bidens comes from the Latin bis (“two”) and dens (“tooth”).

Notes

Note 1 – With around 32,000 species, the Asteraceae is usually considered to be the largest family of flowering plants. The next largest is the Orchid family (Orchidaceae), which has around 28,000 species. The exact numbers are difficult to determine as new species are discovered or reclassified, hence the “probably”.

Note 2 – The Asteraceae is also known as the Compositae, because of its composite flowerheads.

There is a useful glossary on the Kew Gardens ‘Compositae of Bolivia’ web pages.

Strictly, there are six possible kinds of florets, as explained in the Flowers of Asteraceae. (on the website of the South African National Biodiversity Institute).

Note 3 – Bidens tripartita can be quite variable, and there is rare form, var. integra, that doesn’t have trifid leaves. The Wildflower Finder website gives more details.