314 LYCOPODIALES 
and this has been found in Z. zaundatum to go along with a more bulky 
origin. The sporangium as seen in radial section arises as a broad swell- 
ing, while two cells have been seen to divide periclinally, indicating at 
least two tangential rows of archesporial cells in place of the single row 
in Z. Selago. This origin of the sporogenous tissue may still be traced in 
the older stages (Fig. 159). It may be that this condition is not 
actually constant in all cases, but it has certainly been observed to exist 
in L. inundatum. : 
Of the rest of the sub-genus Rhopalostachya, L. clavatum and L. alpinum 
have been examined, and they both show a still more massive type of 
sporangium. This is seen 
in the mature state (Fig. 
160 9, 7, 5S: 4, u,v, Ww), 
where the stalk appears 
to be short and thick: 
moreover, it is seen that 
the strobilus is constructed 
in these species so as to 
afford more complete pro- 
tection to the sporangium 
while young, than is the 
case in the simpler type 
of ZL. Selago. This is 
effected by special de- 
Drawings to illustrate the form and manner of protection of the 
sporangia in the sub-genus Akopalostachya, of Lycopodium. k,l, nt, velopment of the lower 
seonens ot te LAME ERT g, 7, 5, of L. alpinum ; t, u,v, w, of L. parts of the sporophylls 
(Fig. 22 D, E): in some 
cases, as in ZL. cernuum, the sporophyll takes a peltate form. Radial sections 
of the young sporangium show, both in Z. clavatum and in L. alpinum, 
that from the first the form is broader still than in the types previously 
described. At least three cells in each radial section are involved in the 
origin of the archesporium, sometimes even more than three (Fig. 161 a, B). 
Occasionally periclinal divisions appear in the superficial cells, by which 
subsequent additions may be made to the archesporial tissue (Fig. 161 8, 
cells marked x). The tangential sections also show an advance on the 
Selago type: for twelve is not an uncommon number of the archesporial 
cells in one tangential row as against seven in Z. Se/ago, or five in 
L. Phlegmaria. Countings of the sporogenous cells laid bare in sections 
of sporangia at an age approaching the tetrad-condition show that their 
number is far in advance of those of the Se/ago type: this is the condition 
to be anticipated from the bulky character of the sporangia (Fig. 161 c, D): 
moreover, their thicker and shorter stalks would be well fitted to transfer 
the necessary nourishment for the larger spore-output. It may be noted 
that in these large sporangia occasional irregular processes project 
upwards from the base of the sporangium into its cavity, which would 
Fic. 160. 
