Trans. Bot. Soc. Edinburgh 7i 561 1863, 
Squisetu m arvense , Linn., (3 granulatum .- Rhizome bearing at intervals large spherical 
pill-like nodules, stored with starch. 
In the bed of the river Trent, near Trenton, C.W., 7th June 1862. 
This is a remarkable form, differing in aspect from the ordinary state of E. ar- 
vense, and producing its fertile stems a month later. 
