Gymnosporangium clavariiforme

Gymnosporangium clavariiforme is a species of rust fungus which alternately infects Juniperus and hawthorns. In junipers,the primary hosts, G. clavariiforme produces a set of orange tentacle-like spore tubes called telial horns. These horns expand and have a jelly like consistency when wet. The spores are released and travel on the wind until they infect a hawthorn tree. On the secondary hosts, the fungus produces yellowish 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.