Meadowsweet Rust Gall

Fungus / parasite
effuse colony of Cladobotryum anamorph of Cladosporium uredinicola parasitises uredium of Triphragmium ulmariae

Foodplant / parasite
pycnium of Triphragmium ulmariae parasitises leaf of Filipendula ulmaria

Triphragmium ulmariae (Schum.) Link, in Wilid
Sp. PI. 6' : 84. 1825.
Uredo Ulmariae Schura. Knum. PI. Saell. 2 : 227. 1803.
Uredo Spiraeae Sow. Engl. Fungi;)/. 398. 1803.
Puccinia Ulm.ariae Hedw. f.; Poir. in Lara. Encyc. 8 : 245. 1808.
Uredo effusa Ulmanae Strauss, Ann. Wett. Ges. 2 : 91. 1810.
Coleosporium Spiraeae P. Karst. Not. Sallsk. Faun. Fl. Fenn. Forh. 8 : 222. 1866.
Caeoma Ulmariae Thum. Bull. Soc. Nat. Mosc. 531; 220. 1878.
Pycnia epiphyllous, few, flat, reddish-yellow, inconspicuous, subcuticular involving the lateral walls of the epidermal cells, about 350 /^ broad by 60 /i high.
Uredinia at first (primary) amphigenous, more abundant below, indefinitely and irregularly extended, large, 3-5 mm. broad by 5-15 mm. long, usually on the veins and petioles causing hypertrophy and discoloration, soon naked, slightly pulverulent, bright orange-yellow fading to pale-yellow, ruptured epidermis conspicuous ; paraphyses none : uredinia afterward (secondary) hypophyllous and chiefly on the mesophyl, definite, round, small, 0.5 mm. across, not causing hypertrophy, soon naked, very pulverulent, lemon-yellow; paraphyses encircling the sori, cylindrical, 8-15 by 32-50 /i, the wall colorless, thin, less than 1//; urediniospores broadly ellipsoid, or obovate, 18-24 by 25-33 /u ; wall nearly colorless, moderately thick, 1.5-3 M, sparsely echinulate with low, conical points becoming smaller and inconspicuous at base, the pores scattered, very obscure. Telia caulicolous and hypophyllous, arising at first from uredinial sori, on hard tissues large, up to 15 mm. long, on soft tissues small, round, 0.5 mm. across, soon naked, pulverulent, chestnut-brown, ruptured epidermis noticeable ; teliospores laterally flattened, seen flatwise discoid or triangular, seen edgewise obovate, 30-45 by 35-48 fi, rounded above and below, slightly or not constricted at the septa, 3-celled, one cell below and two cells above, all of nearly equal size; wall chestnut-brown, moderately thick, 1.5-2.5 /i, irregularly verrucose with hyaline beads, especially about the pores ; pedicel colorless, once to once and a half length of spore, fragile, largely deciduous.
On Rosaceae :
Filipendula rubra (Hill) B. I^. Robinson {Spiraea lobata Gron., 5. rubra Britton, Ulmaria rubra Hill), Indiana. Type locality : Island of Zealand, Denmark, on Spiraea Ulmaria.
Distribution : I^afayette, Indiana, in one locality of less than a half hectare extent ; also in Europe and Japan.

Triphragmium ulmariae is a species of rust fungus in the family Sphaerophragmiaceae. It causes meadowsweet rust gall, which develops as a chemically induced swelling, arising from the lower surface of the meadowsweet (Filipendula ulmaria) leaves.