290 LYCOPODIALES 
are disposed in radiate fashion around its distal end, which is usually 
enlarged. The whole structure, which is called a “sporangiophore,” may 
be inserted directly on the axis, as in the Agudsefa/es, or upon the appen- 
dages of the axis, as in the Sphenophyllales (including the Psilotaceae). In 
the latter case the position is, as a rule, in the median plane of the 
subtending leaf; but in cases where the sporangiophore is more elaborate 
and shows indications of branching the position may be less obvious. 
Extreme elaboration of the sporangiophore, sometimes including its branch- 
ing, is seen in the series of the Ophzoglossales, which appear as the most 
advanced examples of this pedicellate or Sporangrophoric Type. 
In a third series, the /idcales, the sporangia are usually grouped in 
“sori,” which have features in common with the sporangiophores, but they 
differ from the sporangiophoric types in that the sori are distributed over 
the margins or surfaces of the leaf itself, which is here of relatively large 
size and complex construction. 
The order of description will follow the sequence thus laid down, and 
it will become apparent that the elaboration of the leaves themselves 
follows roughly parallel with that of the sporangial arrangement : in fact the 
whole series may be regarded as progressing from simpler to more complex 
types of the whole shoot. The arrangement thus adopted is convenient 
for description. The question will be reserved for later discussion how far 
it indicates a true evolutionary progression. 
LYCOPODIALES. 
L. General Morphology. 
These plants are taken first because in them the spore-producing members 
are more simple and regular in their disposition on the shoot than in any 
other Vascular Plants. Throughout this phylum (as now limited by the 
exclusion of the Psilotaceae), each single sporangium is subtended by a 
sporophyll (Frontispiece), the median planes of the sporophyll and of the 
sporangium coincide, and typically no more than one sporangium is 
associated with each sporophyll.1 These appendages are borne laterally 
upon the axis, which is endowed with apical growth. The arrangement 
of the appendages, either sterile or fertile, is sometimes in regular 
whorls, but frequently it is according to some more or less interrupted 
spiral scheme (Fig. 141). The axis may undergo frequent branching, 
typically in a dichotomous manner, though intermediate steps are seen 
in certain species to the monopodial type: in some of the Lycopodiales, 
however, branching is rare, or absent. It is thus evident that the whole 
shoot is of a simple strobiloid type. It bears roots at its base, and in the 
‘Occasional exceptions have been noted, where two small sporangia, side by side, are 
subtended by a single sporophyll. These are rare, and appear to originate in some form 
of fission of the normal sporangium (Aznads of Bot., xvii., p. 278). 
