600 FILICALES 
mentioned by Prantl himself as an uncertain member of this sub-tribe. 
An examination of its sorus shows the sporangia of various ages intermixed, 
and without definite orientation. On these grounds the affinity of this 
genus would appear to be elsewhere than in the Dennstaedtiinae. 
ANATOMY. 
It has long been known that the axes of Dennstaedtia and of Microlepia 
show the structure now recognised as solenostelic ; but the detailed know- 
ledge has lately been extended by Mr. Gwynne-Vaughan,! and made the 
subject of important comparisons, of which the following paragraphs are 
a brief abstract. The solenostele is itself held to be a relatively primitive 
state: all the species of Dennstaedtia that have hitherto been examined 
Fic. 333 4. Fic. 333 2. 
Dennstaedtia (Dicksonia) punctiloba, Dia- Dennstaedtia (Dicksonia) adiantotdes. Diagram of 
gram of vascular system of rhizome, including vascular system of rhizome, including a node and the 
a node and the base ofa leaf-trace. The upper base of a leaf-trace. Zs. =lateral shoot arising from 
surface of the rhizome would face the observer. basiscopic margin of leaf-trace: “s.=ridge upon 
(After Gwynne-Vaughan.) internal surface of solenostele. The upper surface 
of rhizome would face the observer. (After Gwynne- 
Vaughan.) 
prove to be essentially solenostelic: similarly all the reputed species of 
Microlepia that have been examined are also typically solenostelic, with 
two exceptions only: one of these is Davallia (Microlepia) hirsuta, Ak, 
which is dorsiventrally dictyostelic, and this appears structurally out of 
place among the AZcro/epias: an examination of its sorus, however, shows 
that the plant is one of the Mixtae: thus both the anatomy and the state 
of the sorus show that its proper place is elsewhere, probably with Dazvaliia. 
The other exception is Davaliia (Microlepia) pinnata, Cav., which appears 
to have relations anatomically rather with Zevdsaya. Excluding these it 
may be said then that solenostelic structure is typical for Dennstaedtia 
and Aicrolepia. 
The vascular relations of leaf and axis are indicated by the Figs. 333 
A, B, Cc. The leaf-trace is in all cases an undivided ribbon-like strand : 
where it is inserted upon the tubular solenostele the latter opens, forming 
the foliar gap, which is here only short, and soon closes (Fig. 333 A). 
1 Ann. of Bot., xvii., p. 689. 
