304 FALSE LEAVES ARE STEMS. FDOOK i. 



through the leaf, without throwing off side branches. What 

 botanists call folium acerosum might be characterised by this 

 circumstance alone. They also have, in most cases, one or 

 two resinous canals, which run through the leaf from end to 

 end ; the leaves of Abies balsamea have such canals near the 

 edge. Those of Thuja occidentalis and Juniperus communis 

 have but one below the principal nervure. Many have a 

 double layer of epidermal cells, as Abies balsamea, and 

 Juniperus Sabina, the cells beneath which are also lengthened 

 laterally, as in some Proteads. In these cases we have a leaf 

 possessing great permanence, and a very high power of 

 vitality, reduced to a cylinder or plate of parenchym, one 

 single fibro-vascular bundle, and a canal to receive the secre- 

 tions as they form in the leaf. From such a leaf it is easy to 

 pass to the more complicated structure of ordinary foliage. 



Some plants produce FALSE LEAVES instead of real ones. 

 Such leaves are always modified branches. They occur in 

 the Asparagus, the Furze, some Colletias, where they are 

 commonly mistaken for leaves, the functions of which they 

 certainly perform, and in various other instances. Among 

 Indian Figs (Cactacese), they are often thin, flat, crenated 

 plates, jointed end to end; in some Spurgeworts (Euphor- 

 biacese) as Xylophylla, they are lanceolate, serrated, hard, 

 straight-veined blades. These false leaves are known by 

 several characters. 



1. They proceed from the axil of a rudimentary leaf. 



2. They bear leaves, or at least flowers, at their notches, 

 whence also they emit fresh shoots. 



3. The veins which run from the midrib to the marginal 

 notches terminate in the axil of the notch, and not at its point 

 as in true leaves. 



Zuccarini gives the following account of them in Phyllo- 

 cladus, a genus of Australian Conifers, (Ray Reports, p. 37). 



" In Phyllocladus, true leaves are entirely wanting, their 

 place being supplied merely by scales of buds or foliaceous 

 twigs. The principal axis of the stem, or of the branch of 

 this plant, produces buds with scales, which are either narrow 

 and linear, or acicular, membranous, and expanding. They 



