458 Arber . — On the Leaf Structure of certain Liliaceae , 
Section VI. NECTAROSCORDUM, Lindl. 
A. Dioscoridis, Sibth. et Sm. (Fig. 30). 
Section VII. MlCROSCORDUM, Maxim. 
A. Monanthum , Maxim. (Fig. 31). 
There is a strong general similarity between those members of the 
first three Sections which I have been able to examine. The leaf is 
differentiated into a basal sheath and a definite limb, the boundary between 
these two regions being marked by a distinct ligule (Figs. 22 A, 23 A, 25 A). 
The limb may be linear and flattened as in A. Porrum (Fig. 22 A and b) ; 
or broad and flattened as in A. victorialis (Fig. 25 a) ; or tubular and more 
or less semicircular in section as in A. fistulosum (Fig. 23 A and c). The 
peculiar hollow leaves of certain Onions have attracted the attention of 
botanists from the earliest days ; their existence was recorded by Theo- 
phrastus 1 (born 370 B.C.). In all the cases which I have examined in 
Sections I, II, and III, the anatomy of the limb — whether flattened or 
cylindrical— is definitely phyllodic, with inverted as well as normal bundles 
{i.b. in Figs. 22 B and C, 23 C, 24 B, and 25 B). The flattened apical region 
of the limb of A. fistidosum (Fig. 23 D) may be closely compared with the 
phyllode of Acacia leptospermoides , Benth. (Fig. 27), which is unusual for 
that genus in being expanded in the horizontal plane. 2 
Allium carinatum , the only member of Section IV ( Macrospatha ) 
which I have studied, differs slightly from the species hitherto mentioned 
in not possessing a ligule, but there is a sharp distinction between the 
limb and the sheath with its membranous wings (Fig. 26 A). The usual 
inverted bundles occur in the limb (Fig. 2 6 B). 
As far as my examination goes, I should say that in Sections I-IV of 
the genus we have leaves which include both leaf-sheath and limb, the latter 
being a petiolar phyllode. Section V (Molium) is more puzzling. In 
Allium Moly , the Lily Leek, there is a sheath, which is swollen at the 
base, then a slender region looking externally like a petiole, and then 
a relatively broad limb. But sections reveal the fact that the ‘ petiole ’ 
(Fig. 29 b) is not a solid structure, but is merely the upward continuation of 
the rolled leaf-sheath (Fig. 29 a), and that the ‘blade’ (Fig. 29 c) is also 
nothing but a direct prolongation and expansion of the sheath. Any sharp 
distinction between sheath, petiole, and blade seems to be purely arbitrary. 
The blade is non-phyllodic in anatomy, containing a single series of bundles 
(Fig. 29 c). The blade of A. Chamaemoly is also similar in structure. The 
curious inverted limb of Allium ursinum (Fig. 38) also shows no trace of 
phyllodic anatomy (Fig. 28 e), while the petiole with its single arc of 
bundles (Fig. 28 c) looks as if it corresponded to the dorsal side of the 
sheath. 
1 Theophrastus: ‘Enquiry into Plants/ trans. by A, Hort. Loeb’s Classical Library, 1916, 
vol. i, p. 77. 2 Hoehreutiner, G. ( 1896 ). 
