390 JOUENAL OF THE ROYAL HORTICULTURAL SOCIETY. 



ciilaceae, &c.) have a common indistinguishable meristem. In 



Amentaceae, Proteaceae, Casuarineae, and some Leguminosae there 

 is plerome, periblem, and epidermis, periblem forming the rootcap. 



Monocotyledons. — In a few {Hydrocharis, Pisiia) there are all four 

 layers. In others {Alisma, &c.) the rootcap is formed by a calyptrogen 

 arising from the dermatogen. 



In others there is only plerome and common initials for the other 

 tissues. 



In Viscum there is no special histogenous layer, and Cuscuta has 

 initial cells which act like apical cells. 



The author points out that the rootcap layers can have no value in 

 classification.— G. F. S. E. 



Rose Black Mildew (Peronospora sparsa). By A. Bretschneider 



(Oestr. Gart. Zeit. vol. vii., pt. vi., pp. 223-226). — Spraying with 

 Bordeaux mixture marks the leaves of the roses ; copper soda mixture 

 has not this disadvantage. The copper soda mixture must not be acid ; 

 if it turns litmus paper red, more carbonate of soda must be added. 

 ** Tenax " and " Cucasa " are also effective; the latter does less damage 

 to the foliage than any other preparation. The disease may be arrested, 

 but cannot be cured by these means. Healthy roses can be protected 

 by spraying with these copper preparations. — S. E. W. 



Rupicola sprengrelioides {Bot. Mag. t. 8438).— Austraha. 

 Family Epacridaceae ; tdbe Epacrideae. Shrub, 2^ feet high. Leaves 

 linear-lanceolate ; flowers white. — G. H. 



Rusts in the United States, Timothy. By Edward 0. Johnson 

 {U.S.A. Dep. Agr., Bur. PI. Ind., Bull. 224, 1911).— Timothy Eust is 

 very similar in general appearance to Puccinia graminis in wheat. It 

 attacks both leaf and stem, forming long yellowish-brown uredo | 

 pustules, and dark brown to black teleuto pustules, which rupture the 

 epidermis. The aecidial stage is not known. 



The rust can be easily transferred to A vena sativa and a number of j 

 grasses, but cannot directly infect Triticum viilgare. By the use of | 

 bridging species the rust undoubtedly could be made to transfer to many I 

 grasses on which it w^ould not grow when coming directly from timothy, 

 and by means of Festuca elatior the rust was transferred to Triticum 

 vulgare. The author points out that Timothy Eust is spreading in the 

 States, and that steps should be taken for its control, the only method j 

 being to raise resistant varieties. This work has been begun. 



D. M. C. 



Rusts of Grains in the United States. By E. M. Freeman 

 and Edward 0. Johnson {U.S.A. Dep. Agr., Bur. PI. Ind., Bull 216, 

 1911). — The rusts of so-called small grain crops are amongst the most 

 serious diseases of plants. This Bulletin represents an attempt on 

 the part of the authors to show briefly our present knowledge of rusts 

 in U.S.A. in comparison with our knowledge of rusts in Europe. 



