274 GRASSES OF IOWA. 



with severe winters, the mycelium, except under favorable con- 

 ditions, is not perennial. 



CROWNED RUST. 



Puccinia coronata. — This is a well-known destructive rust of 

 oats and several other grasses and has received considerable 

 attention from early mycologists. Klebahn* has recently 

 described this rust under several distinct forms. The P. 

 coronata dactylidis in a narrow sence includes the rust upon 

 Daciylis glomerata or orchard grass, Festucasylvatica wi\h a3cidia 

 on Rhamnus frangula and P. coronifera Ericksson and Henning 

 distribute these forms into P. coronata I, and P. coronata II. 

 Historically this rust is of considerable importance, since 

 Gmelint was familiar with this disease in 179 , and described 

 it as Aecklium rhamni on Rhamus. Other early mycologists 

 described the fungus, as Per soon, Schumacher, Lamarck and 

 DeCandolle. The AecidiiDii rhamni Gmel. produces round or 

 elongated spots with elongated, conspicuous ascidia. The 

 spores from 18 to 25" by 14 to 19". The uredo sori are long, con- 

 fluent, mostly on the upper surface of the leaves, seldc m on 

 the under surface of the leaf. They are orange-colored, ai d 

 are soon exposed. Each pustule contains a large number of 

 one celled, sub-glob' se, roughened spores. The spt res are 

 sjjherical or sbort, elliptical. The plant is yellow, £0 to 32" in 

 diameter by 28 to32" by ^0 to 24". The teleuto sj^ores remain 

 covered by the epidermis, and in this ^respect they resemble 

 the covered rust of wheat (Puccinia glnniarum). They usually 

 occur on both sides of the leaf. The spores are she rt stalked, 

 cuneate and more or less truncate above, crowned with several 

 projecting horns. The a!cidium stage occurs on a species of 

 buckthorn' (Rhamnus) especially (R. Vathartica and R. frangula). 

 In this state an secidium is frequently found on a native buck- 

 thorn {R. lanceolata), but its connection with this host has not 

 been studied. The tecidium attacks not only the leaves, but 

 occurs on mid-vein, petiole, pedicels and flowers. As a result 

 of the attacks, distorted leaves and flowers are produced. A 

 few years ago Hon. C. V. Stout, of Parkersburg, in this stale, 

 reported to me some interesting facts with reference to the 

 attack of rust and hedges of buckthorn. 



♦Zeltschraft f . Pflanzenk. 4: 120. 

 tLlnn. Sept. Nat. 2: 1462. 



