294 Bower. — Notes on the Morphology of 
Ophioglossales were derived from a primitive Fern stock, and the sequence 
be, as the anatomical comparison indicates, from a type like Botrychium 
virginianum with relatively numerous smaller sporangia through types such 
as B. ternatum and Lunaria with fewer and larger sporangia, to Ophioglossuni 
itself, it is plain that we are contemplating a progression which is the direct 
converse of that illustrated by the Ferns at large. Such a progression is of 
course possible. The question is whether it is probable. The apparent 
improbability of it weighed with me strongly in previous discussions on the 
phyletic position of the Ophioglossales. 
There is, however, a further circumstance which makes this difficulty 
less serious than it at first appears. It lies in the fact that in Ophioglossum 
a single initial cell is found at the apex of its stem and root. The leaf-apex 
and the structure of its margin, on the other hand, approaches that of the 
Marattiaceae, and is in accord with the bulky sporangial structure. A com- 
parison may be drawn of the meristematic conditions seen in the various 
groups of Ferns . 1 In the Marattiaceae all the segmenting parts are bulky 
and complex in their cleavages ; in fact the centre of construction lies deep. 
In the Osmundaceae a middle position is seen between the state of the 
Marattiaceae and that of the Leptosporangiate Ferns, and this applies here 
also to all the segmenting parts. In the Leptosporangiate Ferns themselves 
a more definite scheme of cleavage is found in all the meristems, which is in 
accord with the definite segmentations of the attenuated sporangium ; in 
fact in them the centre of construction is more superficial. In all of these 
the various parts share the character consistently of a definite or a less 
definite reference to single initials. But the Ophioglossaceae show a dis- 
crepancy which does not find its match in any of the true Filicales. For 
the leaf and sporangium resemble the Marattiales in their more complex 
cleavages, while the apices of stem and root have each a single initial as in 
the Leptosporangiate Ferns. This discrepancy might be referred either to 
a progressively more bulky modification of the leaf and sporangium in 
a plant derived from a type resembling the Osmundaceae, or to a conser- 
vatism by which the plant has retained the characteristics of some remote 
ancestry in its leaf and sporangium, while the axis and root have taken on 
the characters of later forms. In view of the peculiar biological conditions 
of the family, and especially of the tendency towards saprophytism in the 
genus Ophioglossum , I am inclined to the former alternative, and to look in 
the direction of the Osmundaceae and Botryopterideae for the nearest 
relatives of the Ophioglossaceae. 
There are various other comparative points which indicate collectively 
a relation, however distant, with early types of the Filicales rather than with 
the Sphenophyllales, such as the hairiness in the apical region, especially 
as seen in O. palmatum , the conformation of the leaf-base and the vascular 
1 See Land Flora, p. 650. 
