256 



I'll < I XI A 



with bhre ■ four inconspicuous germ-pores; paraphyses very 



few or want ing. 



Teleutospores. Sori hypophyllous, sometimes arranged in 

 circles round the uredo-sorij rarely scattered, occasionally con- 



Fig. lfl-5. P. Lolii. .Ecidia on leaves of /.'. catharticus : Teleutospores, 

 a, on Lolium, b, on Arrhenatherum. 



fluent, oblong or linear, ^ — 1 mm. long, nearly always covered 

 by the epidermis, black ; spores as in P. coronata, but very 

 irregular; mesospores also occur. 



.Ecidia on Rim minis catharticus, May and June: uredo- and 

 teleutospores on Alopecurus pratensis, Arrhenatherum elatius, 

 Avena fatua, A. pratensis, A. sativa, Festuca elatior, Glyceria 

 aquatica, Holcus lonatus, H. mollis, Lolium perenne; not yet 

 recorded on all these species of grass in Britain. (Fig. 195.) 



The Crown Rust of the Oat is most commonly found on Rye-grass, 

 frequently also on Arrhenatherum and Holcus, and also on cultivated 

 Oat which alone of the cereals it attacks, doing considerable damage. 

 The teleutospores can be found on Arrkenatlierwn from the middle of 

 August onwards and, as Plowright remarked, are "accompanied by a 

 profuse development of uredospores "— so profuse, indeed, as to attract 

 the notice of even non-botanical eyes. The uredo-sori form more blister- 

 like swellings and the teleuto-sori remain longer covered by the epidermis 

 than is the case in P. coronata. The uredospores are much brighter in 

 colour than those of P. graminis. 



This species has been divided by Eriksson into a varying number of 

 biological races, of which P. Lolii .1 venae is the most important ; see p. 68. 

 It is found in Australia on Oat and Rye-grass (introduced with seed ?) 

 although no species of Rhamnus is indigenous there (McAlpine). 



DISTRIBUTION: Europe) Asia. North America. Australia. 



