Fungi can be placed into one of three rough groups based on their temperate tolerance. These groups are rough in that they overlap and there is no agreement on their boundaries. They are the psychrophile, mesophile and thermophiles.
Psychrophiles can grow below 5°C but may still have a high optimum temperature similar to a mesophile. Many fungi that cause food spoilage in cold stores belong in this group.
Mesophiles do not grow at low temperatures or at high temperatures above 45°C. Their optimum growth is usually between 25° and 37°C. The great majority of fungi fall into this group.
Thermophiles can grow at high temperatures (45°C to 75°C) with an optimum between 55°C and 65°C and little growth below 40°C. True thermophiles are unable to grow at temperatures below 20°C.
Amongst the mesophiles there are species which border being thermophiles and can live in the higher temperatures of decomposing compost and hay bales. Ones such fungus is usually a wood decay fungus, Schizophyllum commune, but which also grows in decomposing, plastic wrapped hay bales. Below is a temperature graph for S. commune with an optimum growing temperature in the mid 30s.
Composting bins can create high temperatures that are favoured by these borderline thermophiles. Here are two of my bins, at the end of last winter (September 2011), which I had filled with mulched perennial cuttings.
Several weeks after filling the bins they were hot from the decay process and white with fungal hyphae. One morning, 4 September, I lifted the lid on one of the bins and found young expanding caps of what I think is Coprinus macrocephalus. Roger Phillips records it growing on dung-heaps and rotting straw. Coprinus fruitbodies are short lived typically expanding rapidly in the morning and having collapsed by the evening of a single day.
Photo 1 – 9.24am: Stipes have elongated but the cap is yet to expand.
Photo 2 – 11.45am: The caps are beginning to open, some radial splitting, and in the tallest one the margin is beginning to roll upwards.
Photo 3 – 1.34pm: Caps are fully open, with a lot of radial splitting and the margin rolling back.
Photo 4 – 4.23pm: Where near the end as the caps are beginning to autodigest and liquefy. The caps soon dissolve away and the stipes collapse.
Why do they autodigest? One suggestion is that the gills bearing the spores are tightly packed so as they bein to liquify and roll back the distance between the gills increases allowing the spores to drop out and be carried away by the wind. There is also the possibilty the liquified tissue, which is black because it is a suspension of spores, adheres to insects that walk through it, and feed upon it, and they can carry the spores away. Read more about this process written by Lepp and Landsman.
Lepp H 2011. Spore discharge and dispersal in mushrooms. Australian Fungi Website, Australian National Botanic Gardens, Australian National Herbarium. http://www.anbg.gov.au/fungi/spore-discharge-mushrooms.html
Landsman J 2009. The dish on deliquescence in Coprinus species. Cornell Mushroom Blog. http://blog.mycology.cornell.edu/?p=234
Last Friday, 18 May 2012, I went for a stroll with Simon Morton from Radio New Zealand’s This Way Up programme [you can listen to it here]. Simon and I had been emailing back and forth to find a time to get out and look for some mushrooms. However, the cool grey summer followed by a mild dry autumn we have just had meant there had been very little fungal activity. Generally, the best flush of mushrooms occurs when there has been a hot dry summer followed by a cool wet autumn. So it was with a little desperation that I met Simon at the Kelburn cable car entrance to the Wellington Botanic Gardens.
We stopped first to look under a silver birch by the Carter Observatory (see my blog about mushrooms to be found under silver birch in New Zealand). There was a single specimen of Lactarius glyciosmus (coconut milkcap). This is a mycorrhizal species found only under silver birch. Mycorrhizal fungi grow around and between the root cells of the silver birch providing mineral nutrients to the host tree in exchange for complex carbohydrates that the fungus cannot make for itself. Together the tree and the fungus have a symbiotic relationship and neither can survive without the other. Species of Lactarius are easily recognised by cutting the tissue of the gills or stem and observing whether a white fluid flowing from the cut. As Simon noted this fluid is like the milky sap from the cut stem of a dandylion. This also appears to be the first record of this species from the North Island.
We then walked down a track towards the Glen which looks to be surrounded by native bush. Growing on a bank on the side of the track was a bolete. Boletes are distinguished from other mushrooms by the presence of pores rather than gills. Boletes are also usually mycorrhizal. I asked Simon to have a hard look at the vegetation around us and although it looked like native bush about four or five metres away was a big old Pinus radiata. The roots of this pine ran all under this piece of bush. The bolete is Suillus granulatus (sticky-bun bolete).
Two other mushrooms I saw that day, but not mentioned on the programme, were growing on grass under another big old Pinus radiata. Here I found some Amanita muscaria (scarlet flycap). I generally expect to see A. muscaria fruiting in March and early April so these are quite late in the season.
The other species is Russula amoenolens (pine chalkcap). Russula and Lactarius look very similar and are closely related but Russula species never bleed milky sap when cut. This is a European name and has been applied to this fungus under Pinus radiata both here and in its native California however, I believe that it will prove to be an independent species rather than the This European species. There is also another very similar species Russula, R. sororia, under English oak in New Zealand.
I mentioned to Simon how I keep specimens of each species for future reference. I do this by first recording the shape and colour of the fresh mushroom and then I dry the mushrooms to preserve them. The dried mushrooms are stored in zip lock plastic bags to protect them from moisture, which would let them go mouldy, and from insects, such as booklice. Piece of the dried mushroom can be soaked in water and examined under a microscope to record microscopic details that I don’t often have time to do when the mushroom is fresh. Having a dried specimen means that I can go back, at a later date, to check my identification if there are any doubts. Dried specimens are housed in a herbarium. New Zealand has two fungal herbaria one at Landcare Research in Auckland and the other at Scion in Rotorua.
Dianne John sent me some photos of two species of mushrooms under silver birch one of which I had not seen before. European silver birches are a common and prominent tree in the New Zealand urban and rural landscape. The oldest tree recorded by Notable Trees of New Zealand was planted around 1870 in Blenheim (MR/P0026). This along with my blog on birch bolete has prompted me to pull together this list of mushrooms associated with silver birch in New Zealand.
The three most common mushrooms are Amanita muscaria, Leccinum scabrum, and Paxillus involutus:
Amanita muscaria (scarlet flycap). The scarlet flycap is probably the most common and obvious mushroom in New Zealand as it is found associated with silver birch and Pinus radiata as well as many other species of trees. Because of the chemical cocktail that this species contains they are not edible.
Leccinum scabrum (birch bolete): I have discuss the confusion around this fungus in a previous blog where I noted that blueing occurred in the bruised or cut stipe tissue. If this is a single species then it is not L. scabrum. On the other hand if it is two species then the non-blueing fruitbodies belong to L. scabrum while the bluing fruitbodies belong to another species. Birch bolete is considered a desirable edible. The specimen in the photo here is a collection from Pollard Park, Blenheim (13 May 2012) and note that even after 12 hours there was no blueing of the bruised tissue.
Paxillus involutus (birch rollrim): Although usually found with silver birches I have seen it associated with elms in front of the Otago Museum in Dunedin. As its name implies the edge of the cap of this mushroom is strongly rolled under and they and usually funnel shaped. They also have a brown spore print. Edibility is uncertain in this species with some reporting the breakdown of the circulatory system so best avoided. I usually see these in my backyard under the silver birch but there has been no sign of them this year.
Lactarius glyciosmus (coconut milkcap): Dianne John’s photo is the first time I had seen New Zealand material of this species. So last Sunday I headed (13 May 2012) off to Pollard Park in Blenheim and the first thing I saw under the silver birch by the road side was coconut milcaps. Then on Thursday 17 May I was in Wellington Botanical Gardens and there it was again. McNabb first described it from Dunedin and described it as acrid to taste and smelling of coconut. Generally considered not edible.
Lactarius pubescens (downy milkcap): Like L. glyciosmus this was not one that I knew but while looking for the latter I found it under a silver birch down by the stream in Pollard Park. A very distinctive species with its downy surface that is flushed pinkish apricot, especially in the upper stipe and bleeds when cut. Edibility uncertain so best avoided.
Lactaris turpis (smoker-lung milkcap): Yet another milkcap is recognised by it dark motley cap and is sometimes known as the ugly milkcap. I have only seen this under silver birch in Dunedin. A good identification test is a drop of ammonia solution on the cap which immediately goes brilliant purple. Generally considered not edible.
Always remember if you are uncertain about your identification don’t eat it.
McNabb RFR 1971. The Russulaceae of New Zealand. 1. Lactarius DC ex S.F. Gray. New Zealand Journal of Botany 9: 46-66.
NZFUNGI Landcare Research PDD87001
In 1996 I was working at Forest Research in Rotorua when Jack Simpson, a visiting Australian mycologist, pointed to a mushroom under silver birch and asked “what’s that?” Like most New Zealand mycologist I said birch bolete (Leccinum scabrum). He looked at me quizzically, the way that only Jack does, and said “Is it?” The stem flesh turned blue when exposed to air. All of the descriptions of Leccinum scabrum say the flesh is unchanging and certainly does not blue.
The only scientific description of New Zealand specimens of this bolete was by McNabb (1968). However, it was the illustration by Marie Taylor in 1970 that set the idea that this fungus was Leccinum scabrum firmly in the minds of New Zealanders. From 1970 on it just was and no one questioned the identification again.
In response to Jack’s question I collected more boletes within 30 meters of the original question site from under 15-20 year-old European silver birches. I got that same strong clear blueing that Jack and I saw in the first collection, which then fades to a blue green. On this evidence it is clearly not Leccinum scabum. So did McNabb, who described the flesh as “flesh sordid white, unchanging on exposure to air”, not see the blue discolouration or are we dealing with two species under birch in New Zealand?
Di Batchelor sent me two photos of boletes she had collected from under birch in the Wairarapa. The second photo clearly shows blueing in the insect holes at the base of the stem.
I asked Di if there had been blueing of the stipe tissue when she cut it length wise. She noted a strong blueing in the lower stipe that developed of a number of hours. She also said that there was no reaction at all in the first specimen. So this begs the question of whether blueing is not consistent from collection to collection or these two photos represent two species.
The collection that I looked at from Rotorua differed from McNabb’s description in that he described the “cuticle composed of filamentous, repent, septate hyphae” where as I found it to be an intricate trichoderm. This could just reflect development stages of the fruitbodies that I looked at. I also found that the basidiospores were bigger than any described species in the section Scabra, and that the caulocystidia did not match McNabb’s description.
I have have attempted to key the New Zealand bolete out in the Leccinum keys of Smith, Thiers and Watlings (1967), Kibby (2000), Noordeloos (2009), and Persson (1992) but it just doesn’t fit any of the species. So at this stage all I can say is that we may have Leccinum scabrum but we certainly have another Leccinum species as well.
Kibby G 2000. A user-friendly key to the genus Leccinum in Great Britain. Field Mycologist 1: 20-29.
McNabb RFR 1968. The Boletaceae of New Zealand. New Zealand Journal of Botany 6: 137-176 + 3 plates.
Noordeloos ME 2009.The genus Leccinum in Western and Central Europe. http://www.entoloma.nl/html/leccinum_eng.html
Persson O 1992. Leccinum S.F. Gray. In Hansen L, Knudsen H 1992. Nordic macromycetes, volume 2,: Polyporales, Boletales, Agaricales, Russulales. Nordsvamp. Pp.63-66.
Taylor M 1970. Mushrooms and toadstools of New Zealand. Wellington, AH and AW Reed Ltd.
Smith AH, Thiers HD, Watling R 1967. A preliminary account of the North American species of Leccinum, sections Luteoscabra and Scabra. Michigan Botanist 6: 107-154