214 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 
used. Roots having a crown diameter of from one to two inches produced the 
greatest number of marketable heads. Sand proved a very satisfactory covering 
for the roots ; it blanched the leaves perfectly and promoted the formation of 
compact heads. A steady temperature of about 6o° F. appeared to be the best ; 
lower degrees were found satisfactory but required more time to mature the 
crop. It is necessary to keep the soil moist. The time required for forcing the 
crop was fifteen days. — F. G. A. 
Chinese Plants, New. Arbores Fruticesque Chinenses, Novi, I. By Camillo 
Schneider (Bot. Gaz. vol. lxiii., No. 5, May 191 7, pp. 398-405). — Detailed 
botanical descriptions are given of the following new species and varieties : — 
(1) Deutzia (Sect. Eudeutzia, subsect. Stenosepalae Schn.) Rehderiana, sp. n, 
(2) Spiraea (Sect. Chamaedryon Ser.) teretiuscula, sp. n, 
(3) Malus pumila Mill, var. subsessilis, n. var. 
(4) M. (Sect. Docyniopsis Schn.) docynioides, sp. n. 
(5) Sorbus (Sect. Aria) Ambrozyana, sp. n. 
(6) S. hupehensis Schn. var. aperta, n. var. 
(7) S. hupehensis var. obtusa, n. var. 
(8) 5. hupehensis var. laxi flora, n. var. 
(9) 5. Pratiii Koch. var. tatsienensis, n. var. — R. J. L. 
Chinese Plants, New. Arbores Fruticesque Chinenses, Novi, II. By Camillo 
Schneider (Bot. Gaz. vol. lxiii. No. 6, June 1917, pp. 516-523). — Further 
descriptions of the following new plants are given : — 
(1) Clematis chrysocoma Fr. var. sericea, n. comb. 
(2) C. Delavayi Fr. var. calvescens, n. var. 
(3) C. urophylla Fr. var. obtusiuscula, n. var. 
(4) G. (Sect. Viorna Prtl., ser. Connatae Koch.) Kochiana, n. sp. 
(5) Mahonia Alexandri, n. sp. 
(6) M. caesia, n. sp. 
(7) M. philtppinensis, n, sp. 
(8) M. nivea, n. sp. « 
(9) Schizandra grandiflora var. cathayensis, n. var. 
(10) S. grandiflora var. rubriflora, n. comb. — R. J. L. 
Citrus Disease, A New Bacterial. By H. A. Lee (Jour. Agr. Res. ix. April 
1917, pp. 1-8; 3 plates). — Anew disease of Citrus trees, endemic to Northern 
and Southern California, shows black discoloured areas on the leaves near the 
junction of the leaf blade and the petiole, and causes the leaves to fall prematurely. 
The disease frequently spreads to the twigs and causes them to become shrivelled 
and black. The symptoms resemble frost injury, but it has been found that 
it is caused by a bacterial organism (Bacterium citrarefaciens) , apparently a new 
species. 
The bacterium exists in the parenchyma and destroys cell structure, forming 
large pockets filled with bacterial masses. The germ does not enter the vascular 
bundles. Cultures on artificial media show the bacterium can liquefy gelatine 
and forms white smooth glistening colonies on agar. The bacterium is i*8 by 
•6 p and is flagellate, readily stained with aqueous fuchsin, carbol fuchsin, and 
gentian violet, is Gram negative and not acid fast. — A. B. 
Citrus Thrips, Control of the. By J. R. Horton ( U.S. A . Dep. Agr., Bur. Entom., 
Farm. Bull. 674 ; July 1915 ; 7 figs.). — Of the large number of combinations of 
insecticides tested, the following have given the best results : — 
1. Commercial lime-sulphur. 
2. Sulphur-soda solution. 
3. Commercial lime-sulphur and black tobacco extract (40 per cent, nicotine 
sulphate) . 
4. Black-leaf tobacco extract (40 per cent, nicotine sulphate, 1 part to 
800 parts water). — V. G. J. 
Clematis Stem-rot and Leaf-spot caused by Ascochyta clematidina. By 
W. O. Gloyer (Jour. Agr. Res. iv. pp. 331-342, July 1715 ; plates). — The die- 
back disease of Clematis, well known in England, has been investigated by the 
author, who found Ascochyta clematidina always associated with it. The disease 
affects various hybrids and species differently. The hybrids grown outdoors 
are affected by stem -rot, while in the greenhouse, " where the cuttings are 
propagated," they are attacked by a leaf-spot as well. Clematis paniculata shows 
both forms of rot. The fungus was isolated in pure culture, and reproduced the 
disease when inoculated into the stems of C. J ackmanni and C. paniculata, and 
