424 BOTANICAL GAZETTE [may 
Embryology.—SovugEcEs, in continuation of his work on the embryology of 
Angiosperms, has published several recent contributions. Rheum Emodi*® 
is presented as a further representative of the Polygonaceae. Chenopodium 
Bonus-Henricus# is the subject of an unusually full treatment. Inthe presenta- 
tion of the embryogeny of the Labiatae, Glechoma hederacea and Lamium pur- 
pureum form the subject of one paper,” and in the second paper} Mentha viridis 
is used. The Scrophulariaceae are represented by Veronica arvensis.4 The 
presentation of the embryogeny of Urtica pilulifera*s is completed with two 
papers.—J. M. C. 
Overgrowth of stumps.—The overgrowth of the upper ends of stumps of 
Pseudotsuga and of Abies grandis has been observed by PEMBERTON" in British 
olumbia. Careful excavation showed that in every case root grafting with 
living trees existed, the connected roots providing an avenue for food conduc- 
tion to the stump, and this he believes to be the true explanation of the interest- 
ing phenomenon.—Geo. D. FuLLER. 
Addisonia.—The fourth number completing Vol. 5 of this publication 
appeared in December 1920, and the first number of Vol. 6 appeared in March 
1921. The fine colored illustrations and ae pga ie form a collection 
that should be in every botanical library—J. M 
Potassium and growth of plants.—SmitH and Butier” have published a 
report of rather extensive work on the effect of potassium on the growth of 
plants. It confirms all the old findings and gives quantitative data on several 
new plants.—Wm. CROCKER. 
20 Sources, R., waa sur l’embryogénie des Polygonacées (suite). Bull. 
Soc. Bot. France 67: 75-85. I 
, Dév eae Ae Pe Vembryon chez le Chenopodium Bonus-Henricus L. 
Ibid. 67: Oe Jigs. 40. 1920. 
=. Embryogénie des Labiées. Développement de l’embryon chez le 
Glechoma hedivoces L. et Lamium purpureum L. Compt. Rend 1921 : 48-50 
23 , Développement de l’embryon chez le Mentha viridis L. Ibid. 1921: 
1057, — 
“4. Embryogénie ae oo Développement de I’embryon chez 
le Veronica arvensis L. Ibid. : Le 
pal asiprea bie caus se cose De VUrtica pilulifera L. Bull. Soc. 
Bot. France 68: 172-188; 280-294. figs. 5 
# PEMBERTON, C. C., Overgrowth of oe of conifers. Can. Field Nat. 35:81- 
87. figs. 4. 1921. 
77 Situ, T. O., and Butter, O., Relation of potassium to growth in plants. 
Ann. Botany 35:189-225. 1921. 
