XXXIl] 



LOPHOSORIA 



285 



sorus is small (7-10), arranged in two tiers, and orientated as in Gleichenia, 

 the upper tier being less regular than the lower (Fig. 549). But as the 

 stomium is lateral the shedding of the spores presents no mechanical 

 difficulty. Simple hairs are associated with the sporangia. From this 

 description it appears t\\2ii Lop hosori a holds a position between the Gleicheni- 



h il;. 549. A single sorus of Lopiiosoi-ia, showini; 

 the small number of sporangia, with their regular 

 orientation. Each sporangium has its annulus 

 apparently complete : the stomium is lateral, and 

 therefore out of sight. (Enlarged.) (Drawn by 

 Mr Maxwell.) 



aceous and Cyatheaceous types, in respect of the external characters: but 

 with special similarity to G. pectiiiata. There is, however, an entire absence 

 of those consequences of apical arrest which give to the leaves of GleicJieiiia 

 the appearance of a false dichotomy. 



Anatomy 

 The axis and leaf-stalk are strengthened externally by a dark-coloured 

 band of sclerenchyma, without lenticels. Sclerotic tissue also forms a ring 

 within the solenostele, and straps of it accompany the leaf-traces outwards, 

 lining their concave face. In certain sections there is a perfect solenostele, 

 as may frequently be seen in the runners if cut between the leaf-insertions. 

 The ring opens to give off a leaf-trace in the usual way, and closes almost 

 at once (Vol. I, Fig. 156, p. 163). But in the upright stock where the axis is 

 shorter, there may be an approach to dictyostely, which however is seldom 

 fully realised. A transverse section of a large stock will commonly show a 

 single leaf-gap, but already the stele may be thinning out at another point 

 preparatory to giving off a second leaf-trace, or even a third (Fig. 550). The 

 leaf-trace departs as a single wide gutter-shaped strand, not contracted as 

 in Glcichenia, and it soon assumes the usual horse-shoe with deep involutions 

 opposite the lateral pneumatodes, which are here present as in most large 



