SPORE-PRODUCING MEMBERS 



313 



FIG. 158. 



d, e,f= sections radial, tangential, 

 and transverse of matu 



tissue also as tapetum. The dehiscence is along a transverse line, and the 



preparation for this is already indicated at the distal end in Fig. 157 D, d. 



Meanwhile, the sporogenous group within, in 



the formation of which the whole products of 



the archesporium are involved, has been subject 



to repeated cell-division: its cells finally separate, 



round themselves off, and all of them, as a rule, 



undergo the tetrad-division. In the mature 



sporangium the form is less strongly curved 



in L. Selago than in many other species, while 



the stalk is a relatively narrow one. The 



general proportions, as well as the imperfect 



protection of the sporangium afforded by the 



rather narrow sporophylls, are shown in Fig. 



158 d, e, f. 



The type of sporangium thus described for 

 L. Selago, with its single row of archesporial 



Cells, relatively narrOW Stalk, and imperfect ana transverse ot mature sporangia 



of Lycopodium Selago. g, n, i 



protection while VOUnSJ, appears tO be Character- similar sections of mature sporangia 

 * . . . f Lycopodmm phlegmai'ia. X 12. 



istic, with relatively slight modifications, of the 



sub-genus Urostachya : other species of the sub-genus which have been 

 examined, viz., L. dichotomum, Jacq., carinatum, Desv., nummularifoliitm, 



Blume, and Phlegmaria, L., are all alike in 

 showing an archesporium consisting of a single 

 tangential row of cells, though the number of 

 these in the row may vary ; the simplest case 

 observed was that of L. Phlegmaria, where the 

 single series consisted of certainly not more than 

 five cells, and perhaps of less. The further 

 development in these species was also the same 

 as in L. Selago, though the proportions were 

 different. In L. dichotomum, however, there is 

 the peculiarity that the sporangial wall is found 

 to be more massive, consisting of 4-7 layers. 

 Putting such differences aside there seems 

 reason to regard the single tangential series of 

 archesporial cells as a common feature of the 

 sub-genus Urostachya : further, the sporangia 

 are inefficiently protected by the sporophylls 



FIG. 159. 



Lycopodium innndatuiti, 

 Radial sections of sporangia. 



In 



the upper, younger figure periclinal /Fi" 1^8 " Jl l\ 

 divisions are shown in two cells, and X O" 06' 



the archesporial ceils are shaded. j n p r itzel's arrangement of the genus the 



In the lower, older figure the pro- 

 duct of division of these ceils is section Inundata is separated from Phlegmaria, 



shown. X 200. 



and placed in the second sub-genus Rhopalo- 



stachya. We shall see that the sporangial character upholds this change. The 

 sporangia are from the first more bulky than in Urostachya (Fig. 160 k, /, m\ 



