45 6 Arber. — On the Leaf Structure of certain Liliaceae , 
The genus Johnsonia , which gives its name to the Tribe, differs rather 
strikingly from the other members in its leaf structure and anatomy, since it 
is a typical isobilateral equitant leaf (Fig. 18 A and b), recalling a number 
of Iridaceae, &c., some of which were figured in a previous paper. 1 Its 
interest from the standpoint of the Phyllode Theory is that it furnishes an 
instance of an isobilateral equitant leaf within a Tribe which also includes 
genera characterized by other types of phyllodic leaf. The same thing 
occurs, as I have already pointed out, 2 in the Iridoideae and even within 
the genus Iris . The additional case of Johnso7iia seems to lend colour to 
the view that the isobilateral equitant leaf should not be interpreted as 
a case of congenital concrescence, but that it is merely a special type of 
petiolar phyllode. 
IV. The Leaves of Allium and Brodiaea (Allioideae). 
The majority of the records of phyllodic anatomy among the Liliaceae 
relate to genera belonging to the large Tribe of the Asphodeloideae, which 
possibly represents that group within the family which has retained the 
most primitive characters. The other two main Tribes of the Liliaceae 
proper are the Allioideae and Lilioideae. The Lilioideae — although they 
include certain leaves which I have interpreted as leaf-base phyl lodes 
terminating in a vestigial petiole 3 — do not apparently present any instances 
of typical phyllodic anatomy. The Allioideae, however, include a number of 
cases coming under this head. I propose to consider the genus Allium (as 
representing this Tribe) in some little detail, and to add a brief description 
of one species of the related genus Brodiaea for comparison. 
In the case of Allium I have examined the leaf structure of at least one 
species belonging to each Section of the genus ; viz. : 
Section I. PoRRUM, G. Don. 
Allium Porrum , L. (Figs. 22 A-c). 
A. Scorodoprasum , L. 
A. Ampeloprasum , L. 
Section II. Schoenoprasum, G. Don. 
A. Schoenoprasum , L. (Figs. 24 A and B). 
A. fistidosum, L. (Figs. 23A-D). 
Section III. Rpiiziridium, G. Don. 
A. victorialis , L. (Figs. 25 A and b). 
Section IV. Macrospatha, G. Don. 
A. carinatum , L. (Figs. 26 A and B). 
Section V. Molium, G. Don. 
A. ursinum , L. (Figs. 28A-E). 
A. Chamaemoly , L. 
A. Moly, L. (Figs. 29 A-c), 
1 Arber, A. (1918), p. 483. 2 Ibid., pp. 484-5. 
3 Ibid. (1920 1 ). 
