Triphragmium ulmariae is a species of fungus

Fungus

A fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...

 in the Sphaerophragmiaceae family. It causes meadowsweet rust gall, which develops as a chemically induced swelling, arising from the lower surface of the meadowsweet

Meadowsweet

Filipendula ulmaria, commonly known as Meadowsweet, is a perennial herb in the family Rosaceae that grows in damp meadows. It is native throughout most of Europe and Western Asia...

 leaves.

Cause

This common gall

Gall

Galls or cecidia are outgrowths on the surface of lifeforms caused by invasion by other lifeforms, such as parasites or bacterial infection. Plant galls are abnormal outgrowths of plant tissues and can be caused by various parasites, from fungi and bacteria, to insects and mites...

 is caused by the foliar 'rust' fungus Triphragmium ulmariae (DC.) Link, 1825 .

Appearance

The fungus attacks the petioles

Petiole (botany)

In botany, the petiole is the stalk attaching the leaf blade to the stem. The petiole usually has the same internal structure as the stem. Outgrowths appearing on each side of the petiole are called stipules. Leaves lacking a petiole are called sessile, or clasping when they partly surround the...

 and / or midribs of the perennial meadowsweet

Meadowsweet

Filipendula ulmaria, commonly known as Meadowsweet, is a perennial herb in the family Rosaceae that grows in damp meadows. It is native throughout most of Europe and Western Asia...

 (Filipendula ulmaria) plant, a member of the Rosaceae family, causing swelling and distortion. Sori develop with bright orange spores.

Life cycle

The rust's spores reach the meadowsweet via air movements and are spread from the galls that develop on the petioles and / or midrib veins.

External links

• Wildlife photography.