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27-04-2026 20:52

Lothar Krieglsteiner Lothar Krieglsteiner

Found on hanging tiwg of Olea europaea in dried-ou

27-04-2026 18:48

Tony Moverley

Collected 23rd April 2026, Norfolk, EnglandSwarms

27-04-2026 17:41

Lothar Krieglsteiner Lothar Krieglsteiner

.. Algarve, same leaf than the last post. The con

27-04-2026 18:05

Lothar Krieglsteiner Lothar Krieglsteiner

... still attached at standing tree. The green con

27-04-2026 17:16

Lothar Krieglsteiner Lothar Krieglsteiner

.. Algarve, moist lying.The conidiomata look like

27-04-2026 12:54

Steve Clements

Bonjour. Ce petit champignon blanc résupiné et

27-04-2026 09:59

Pauline. Penna

Bonjour Can anyone advise me on these pycnidia fo

26-04-2026 21:08

William Slosse William Slosse

Several species of Ramularia occur on Rumex that I

22-04-2026 20:54

Enrique Rubio Enrique Rubio

Hi to everybody.This Pyrenopeziza grew in moist le

25-04-2026 11:34

Louis DENY

Bonjour forumdans la clé de Zotto, L. pudicellum

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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