Urocystis Agropyri on Redtop

Abstract

The hosts and host ranges reported by Clinton in North American Flora 7: 58. I906 are as follows: Agropyron divergens Nees (Agropyron spicatum (Pursh) Scribn. & Smith), Washington; A. occidentale Scribn. (A. smithii Rydb.), New Mexico; A. repens (L.) Beauv., Connecticut, Massachusetts and Vermont; Bromus ciliatus L., Iowa; Bromus sp., Minnesota; Calamagrostis canadensis (Michx.) Beauv., Oregon; Elymus arenarius L., Greenland; E. canadensis L., Illinois, Iowa, Kansas, Missouri, Nebraska and Wisconsin; E. robustus Scribn. & Smith; E. virginicus L., Illinois and Wisconsin; E. sp., Colorado and Minnesota. On redtop, the general appearance of the sori on the parts of the plant is the same as described for other hosts. The pustules form on the exposed culm, leaf sheath and blade, rhachis and rhachilla and are especially numerous on the leaves near the top of the culm. Striae, varying from 0.5 mm. in length to that of the whole leaf, form between the leaf veins. When young, these striae are raised and covered with light-colored, epidermal tissue of the host which later ruptures forming a trough-like slit filled with the spore balls. After the dispersal of the spore balls, the tissues beneath the striae become transparent and finally the leaves are shredded longitudinally. The culm above the sheath of the last leaf is usually twisted and the black pustules either remain distinct or coalesce on small areas of the culm. Although the plants when observed were only partially in blossom, many of the highly in279