On the Nature of the ‘Blade’ in certain 
Monocotyledonous Leaves. 
BY 
AGNES ARBER, D.Sc., F.L.S. 
( Keddey Fletcher-Warr Student of the University of London ). 
With twenty-nine Figures in the Text. 
Contents. 
PAGE 
I. Introduction 330 
II. Observations on the Origin of the ‘ Lamina ’ in the Leaf of certain 
Monocotyledons 330 
Helobieae .... Potamogetonaceae . . . Potamogeton . . 330 
Aponogetonaceae . . . Aponogeton . . .332 
Alismaceae Sagittaria . . . 332 
Ilydrocharitaceae . . . Hydrocharis . . 333 
Principes Palmae Areca .... 333 
Oreodoxa . . .333 
Synanthae . ... . Cyclanthaceae Carludovica . . 333 
Spathiflorae . . . Araceae Calla . . . .335 
Arum . . . 335 
Epipremnum . . 335 
Pistia . . .337 
Liliiflorae .... Liliaceae Veratrum . . . 337 
Smilax . . . 339 
Rhipogonum . . 340 
Amaryllidaceae .... Curculigo . . . 340 
Dioscoreaceae Tnmus . . . 342 
Dioscorea . . . 342 
Iridaceae Tigridia . . . 343 
III. Observations on the Origin of the ‘Lamina’ in the Leaf of certain 
Dicotyledons 345 
Aristolockia . . 345 
Polygonum . *345 
Populus . . . 346 
Fagus . . .346 
Cercis . . . 346 
Trifolium . . . 346 
Syringa . . . 346 
IV. Comparison between the Ontogeny of the Blade in Monocotyledonous 
and Dicotyledonous Leaves 347 
V. Classification of the ‘Blades’ of Monocotyledonous Leaves . . . 349 
VI. Summary 350 
List of Memoirs cited 35 x 
[Annals of Botany. Vol. XXXVI. No. CXLIII. July, 1922.I 
