Further Notes on Intrafascicular Cambium in 
Monocotyledons. 
BY 
AGNES ARBER. 
With four Figures in the Text. 
I N a recent number of the ‘ Annals of Botany ’ I drew attention to the 
widespread occurrence of intrafascicular cambium in Monocotyledons. 1 
I have since observed it in several additional cases, including an example 
from each of four families (Araceae, Dioscoreaceae, Iridaceae, and Potamo- 
getonaceae) in which, apparently, it has not hitherto been noticed. The 
object of the present note is to record these cases and to enumerate the 
cohorts and families in which instances of intrafascicular cambium have up 
to the present been observed. 
Acorns calamus , L. (Araceae). In the Sweet Flag transverse sections 
close to the apex of the rhizome show cambial activity within the bundles 
very clearly. The lignified protoxylem and the immature metaxylem are 
separated from the phloem by radial files of cells (Fig. i).. 
Fig. i. A corns calamus, L. Trans¬ 
verse section of single bundle from near 
apex of rhizome, showing radial rows 
of elements between xylem and phloem 
( ph .). Only the protoxylem (pxi) is 
at present lignified. (x 320.) 
Fig. 2 . Tamus communis , Z. Trans¬ 
verse section of single bundle close to 
apex of aerial climbing stem, showing 
radial rows of elements between proto¬ 
xylem (px.) and phloem (phi). ( x 320.) 
Tamus communis , L. (Dioscoreaceae). In the Black Bryony transverse 
sections close to the apex of the growing shoots reveal, within the individual 
bundles, a radial arrangement of the cells between the phloem and the 
lignified protoxylem (Fig. 2), but this indication of cambial activity is highly 
1 Arber, Agnes : On the Occurrence of Intrafascicular Cambium in Monocotyledons. Ann. Bot., 
vol. xxxi, pp. 41-5, 3 Text-figs., 1917. 
[Annals of Botany, Vol. XXXII, No. CXXV. January, 1918.] 
