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31-12-2013 11:00

Alan Rockefeller Alan Rockefeller

Growing on Acer macrophyllum (bigleaf maple).  Se

31-12-2013 01:28

Rubén Martínez-Gil Rubén Martínez-Gil

Hola a todos.El pasado sábado encontramos esta Ot

30-12-2013 19:13

Patrice TANCHAUD

Bonsoir,chaque hiver, sur différentes mousses (li

30-12-2013 23:32

Pavol Palo

Hi everybody, I found this one on decidious wood

28-12-2013 23:24

Michel Hairaud Michel Hairaud

Bonsoir à tous, Hi to everyone,Pour la 2eme anné

30-11-2013 00:23

Elsa Sousa

Hi,Could somebody give me any clues of possible ge

28-12-2013 01:00

Rubén Martínez-Gil Rubén Martínez-Gil

Hola a todos.Pongo unas fotos de este asco que en

29-12-2013 04:30

Byrain

I found these on some dead grasses in an wet envir

26-12-2013 19:59

Enrique Rubio Enrique Rubio

These very small (up 70 125 microns), superficial,

26-12-2013 20:37

Eduard Osieck

Piece of decorticated Fraxinus wood, collected 4 m

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Black dots on maple leaf
Alan Rockefeller, 31-12-2013 11:00
Alan RockefellerGrowing on Acer macrophyllum (bigleaf maple).  Seen at the Yuba Watershed Fungus Fair.

No asci observed. Many parathyses with tiny oil drops were seen, they measured 30 – 45 × 2 – 3 micrometers. Many clavate basidia-like things seen, however they never had sterigmata or spores inside. Those measured (28) 36 – 47 x (5) 7 – 8 micrometers.

  • message #26494
Jacky Launoy, 31-12-2013 12:58
Re : Black dots on maple leaf
Rhytisma acerinum (Pers.:Fr.) Fr.
David Malloch, 31-12-2013 15:34
David Malloch
Re : Black dots on maple leaf
Hi Alan..
That is probably Rhytisma punctatum.  The US host-index lists it on Acer macrophyllum in California, Oregon and Washington.  The "clavate, basidia-like things" are probably immature asci.  These would be mature in the spring at about the time the new leaves are emerging on the tree.

Dave
Byrain, 31-12-2013 16:47
Re : Black dots on maple leaf
Alan, I found that leaf and posted it on MO as Rhytisma punctatum.  I have the other two leaves from that collection also.  I scoped them too and also saw no mature asci.

Here are some more macro images... http://mushroomobserver.org/156379?q=1higi?

Edit:  I understand that punctuate dots like this on Acer macrophyllum = R. punctatum, but there is another species with a somewhat similar appearence on other maples.
http://www.glfc.forestry.ca/VLF/ForumPresentations/hsiangtarspot_08e.pdf