the Monocotyledonous Leaf. 
495 
8 . The significance of the systematic distribution of phyllodic 
leaf anatomy among the Monocotyledons. 1 
The two Monocotyledonous Cohorts, in which phyllodic leaf anatomy is 
at present most widely known, are the Helobiae and the Liliiflorae. In the 
Helobiae phyllode structure has been found in five Families out of seven, 
while in the Liliiflorae it has been recorded in six Families out of eight. 
It is a striking fact that—if the theory be accepted that the Monoco¬ 
tyledons are descended from the Ranalean plexus 2 -—it is these two Cohorts 
which will probably be regarded as including the members of the Class which 
have retained the greatest number of primitive features. Within the Lilii¬ 
florae we find phyllodic characters conspicuously developed in the central 
group—the Liliaceae. Within the Liliaceae the most striking feature in the 
distribution of phyllodic structure is that examples are known from no less 
than six tribes of the Asphodeloideae. This gains significance from the fact 
that the type of seedling structure occurring in Anemarrhena, a member of the 
Asphodeleae, has been regarded by Miss Sargant 3 as probably * primitive 
among Monocotyledons in general as well as among the Liliaceae proper \ 
The Juncaceae, Amaryllidaceae, Haemodoraceae, and Iridaceae show 
every indication of being Families derived from the Liliaceous stock. 
They have, in many cases, retained the phyllodic anatomy which the present 
writer regards as a primitive character among the Liliaceae. In the Iridaceae 
it is perhaps more conspicuously developed than in any other Family, and 
this fact may possibly be taken to indicate that the Iridaceae arose from the 
Liliaceous stock at a period when that * stock exhibited the phyllodic 
character even more markedly than it does at the present day. At the 
risk of seeming far fetched, it may be suggested that the behaviour of the 
Iridaceae in this respect is comparable with the fact that the American 
descendants of the Pilgrim Fathers, who left this country in the seventeenth 
century, have retained a few archaic forms of speech characteristic of the 
England of that period. 
Among the Spathiflorae, phyllodic anatomy is, at present, known only 
in the genus Acorus of the Araceae (and probably in the related genus 
Gymnostachys). It would be unsafe to lay much stress upon this individual 
case, but it is interesting to note that in Acorus the flower is hermaphrodite 
with free perianth members and with the five trimerous whorls character¬ 
istic of typical Monocotyledons. The Pothoideae, to which it belongs, are 
regarded by Engler 4 as representing the oldest Family of the Cohort. It 
may also be recalled that Miss Sargant 3 considered that the Araceae 
could be related by seedling characters to the Liliaceae. 
1 In connexion with this section see the list of cases, pp. 478-81. 
2 See Sargant, E. (1903), &c., and Arber, E. A. N., and Parkin (1907). 
3 Sargant, E. (1908). 4 Engler, A. (1889). 
