362 LYCOPODIALES 
Phlegmaria is believed to be primitive, the turgid developments of Z. 
clavatum, cernuum and tnundatum, and also of Phylloglossum, are believed 
to be secondary. 
The embryogeny of Se/aginella (Fig. 190) corresponds in all essentials to 
that of Lycopodium, and shows only minor distortion or swelling. In the 
simple case of .S. spinulosa the apex of the axis originates as before from 
the centre of the upper tier: the active growth of the first leaf throws 
the apex of the axis to one side; but it is “righted” again on the 
appearance of the second, and the identity of the apex is clearly 
maintained throughout. The whole epibasal tier is then carried upwards 
by intercalary growth of the hypobasal region, but the hypocotyl thus 
formed is without lateral swelling, and the first root originates laterally 
at its base. As regards distortions, this case is quite similar to that of 
L. Selago or Phiegmaria. But in other Se/aginellas, as exemplified by 
S. Martensit, the cotyledons arise equally, as indeed they sometimes 
do in .S. sfinulosa, and the temporary distortion of the apex does not 
appear; but a lateral swelling, absent in S. spzmudosa, constitutes the 
“foot.” Thus Sedaginella shows only minor and finconstant deviations 
from the simple type. 
The embryogeny of Jsve¢es is less easily compared, but the following 
tentative suggestion is given (Fig. 191). The suspensor is entirely absent, 
and the embryo, composed only of the two tiers corresponding to those of 
other Lycopods, is usually orientated so that its apex is from the first 
directed towards the neck of the archegonium. That the rotation necessary 
to bring this about may occur is indicated by the differences of position 
of the basal wall noted by Campbell. The product of the hypobasal tier is 
the haustorial foot only: the upper tier hastens at once to form the large 
cotyledon, with the effect that the stem-apex is delayed, and remains 
minute: it only becomes clearly recognisable after the appearance of the 
second leaf opposite the first. In relative position, however, these parts of 
the shoot correspond to those of S. spimulosa or L. Phlegmaria. The 
first root originates from the epibasal tier as in Lycopodium rather than 
Selaginella, and unlike ZL. Phlegmaria and S. spinulosa on the side opposite 
to the cotyledon; but the orientation of the root relatively to the cotyle- 
don has been seen to vary within the Lycopodiales, so no great importance 
need attach to this discrepancy. The primary embryogeny of Jsvetes may 
thus be held as related to that of the other Lycopodiales, but without a 
suspensor, and greatly abbreviated, and with the apex of the axis correlatively 
reduced and delayed in its development, owing to the early production of 
the cotyledon and the root. Nevertheless, its position at the centre of the 
epibasal tier is maintained. 
It is thus seen that the embryos of all the Lycopodiales may be held 
as variants on a single type, and fundamentally of spindle-like form. 
