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09-01-2026 17:41

Arnold Büschlen

Hallo, F. dilatata wird von vielen Bryoparasiten

10-01-2026 20:00

Tom Schrier

Hi all,We found picnidia on Protoparmeliopsis mur

07-01-2026 22:22

Danny Newman Danny Newman

Tatraea sp. on indet. hardwood The Swag, Great Sm

10-01-2026 01:18

Danny Newman Danny Newman

cf. Neovaginatispora fuckelii on indet. shrub Pre

07-01-2026 10:24

Danny Newman Danny Newman

Pezicula sp. on indet. hardwood Appalachian Highl

09-01-2026 10:08

Blasco Rafael Blasco Rafael

Hola, en el mismo habitat que la anteriorRetamaDia

08-01-2026 21:22

Blasco Rafael Blasco Rafael

Hola, He recogido esta muestra de Orbilia sobre Re

07-01-2026 17:29

Marc Detollenaere Marc Detollenaere

Dear Forum,On a barkless Populus I found some smal

10-11-2021 17:33

Riet van Oosten Riet van Oosten

Add-on topic http://www.ascofrance.com/forum/7059

07-01-2026 10:05

Danny Newman Danny Newman

cf. Chaetospermum on XylariaCosby Campground, Grea

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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