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Gymnosporangium sp. on Crataegus monogyna
This species of Gymnosporangium is a fungus which alternately infects junipers, and afterwards hawthorns. It could be G. clavariforme, G. confusum or G. gracile, but only by microscopy can distinguish between them in the hawthorn phase. In junipers (the primary hosts), some species of these fungi form a ball like gall about 2–4 cm in diameter which produces a set of orange tentacle-like spore tubes called telial horns. These horns expand and have a jelly like consistency when wet. In other species the telia are produced directly from the bark of the juniper with no obvious gall formation or swelling[2] such as in G. clarvariforme . The spores are released and travel on the wind until they infect a hawthorn tree. On the secondary hosts, the hawthorn, the fungus produces yellow-reddish depressions on the leaves. It also infects the fruit, which grows whitish tubes like a Medusa head. These are the spore tubes. The spores must then infect a juniper to complete the life cycle.
On the leaves of Crataegus monogyna (espino albar). Mediterranean forest
Camera Model: NIKON D300. Exposure Time: 1/60 sec. f/32 ISO Speed Rating: 200. Focal Length: 90.0 mm. Flash fired
Spotted on May 29, 2012
Submitted on Jun 8, 2012
2 Comments
Thanks martinl. Yes, they are very remarkable fungi infecting first junipers and then hawthorns. The funny thing is that I have not seen any juniper in the area. Apparently they different hosts can be very far away. Sometimes, fungi are very strange things.
Great spotting and excellent information arlanda. They look like red sores breaking through the plants skin, which is exactly what they are