GENERAL MORPHOLOGY 441 
O. simplex, Ridley.1. This ground-growing mycorhizal plant has tall fertile 
spikes, without any sterile lamina. Anatomically as well as in form it 
resembles O. pendulum; but more especially in its external characters and 
its habit it resembles the rare O. intermedium, Hook, which is also a 
ground-growing species. For reasons explained at length in the paper 
above quoted, it is thought that O. simplex forms the end of a series of 
reduction of the vegetative system consequent on a mycorhizal habit and 
shaded habitat: that as O. zntermedium, when compared with O. pendulum, 
shows a relatively large spike but only a reduced lamina, so in O. simplex 
the reduction having proceeded further has resulted in the complete 
elimination of the sterile blade. 
In the genus Botrychium the construction of the upright stock is 
essentially similar to that of Op/zoglossum, and the plants are habitually, 
though not always monophyllous. The main external difference hes in the 
branched form both of the sterile leaf and of the fertile spike: these parts 
show a similar parallelism of ramification to that which is present though 
less regular in O. palmatum. According to the complexity of the two 
parts the species may be arranged, starting from those very small and 
simple forms included under the name Sotrychium simplex. These are 
held by Luerssen not to be actual varieties, but rather plants of various 
ages, and therefore in different stages of development which pass into 
one another, a point which greatly increases their interest (Fig. 240). The 
sterile leaf in the smallest of these may be entirely unbranched, as in a 
small Ophioglossum, while the fertile spike is also unbranched, and bears 
a very small number of sporangia (Figs. 240 a-F): these appear in the simplest 
cases as individual lateral projections from the spike, but here, as in the 
whole genus, they are disposed along its lateral margins, in the same 
relative position as in Ophioglossum. The steps from this simple condition 
are clearly shown in Luerssen’s drawings (Figs. 240 G-L), lobation of the 
sterile leaf progressing in marked parallelism with branching of the fertile 
spike: first a simple pinnation, and then an incipient double pinnation. 
The condition is thus attained which is seen in the common &. Lwnaria 
(Fig. 241), where the pinnation in its different forms may be single or 
double. And so onwards through the species, the sterile leaf may be 
three (B. daucifolium), or even four times pinnate (2. virginianum), the 
fertile spike showing a corresponding complexity. The whole genus from 
the simplest to the most elaborate, shows such gentle gradations of change 
that the unity of type throughout is unmistakable. 
Various abnormal modifications have been described for Botrychium, 
some of them involving the formation of accessory parts, such a 
doubling of the sterile leaf, or increase in number of the fertile spikes, as 
in Ophioglossum ; but no species of Botrychium is recognised in which this 
is established as a permanent character. The abnormalities involving dis- 
tribution of the sporangia are the most important: all stages of vegetative 
1See Ann. of Bot., 1904, p. 205. 
