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These tiny (0.4-0.5 mm diam.), whitish, short-stip
Black dots on maple leaf
Alan Rockefeller,
31-12-2013 11:00
Growing 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.
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
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
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
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