254 



LOXSOMACEAE 



[CH. 



sorus is of the type of Trichovianes, with a basipetal sequence of the spor- 

 angia borne on an elongated receptacle: a basal cup-like indusium protects 

 the youngest sporangia. But at maturity the receptacle elongates, so that 

 the sporangia are raised above the lip of the indusium, and there dehisce 

 (Fig. 521). But the sporangia of the two genera differ in detail, notwith- 

 standing the similarity of their sori as a whole. In both genera the dermal 

 appendages are hairs. They appear of two types: soft uni-seriate hairs borne 

 upon the leaf-blade, and stiff bristle-like hairs which widen downwards into 

 a multicellular conical base: these are found on the leaf-base, and densely 

 cover the rhizome. There are no flattened scales or ramenta. 



Fig. 522. Loxsoma Cimningliaini. Diagram showing the 

 form ot the vascular system at a node of the rhizome, 

 j-j- = solenostele : // = leaf-trace departing: /i,''= leaf-gap: 

 the arrow points towards the apex of the rhizome. 

 (After Gwynne-Vaughan.) 



Fig. 523. An acropetal series of 

 sections of themeristele oi Loxsoma 

 showing its modifications towards 

 the apex of the leaf (After G w ynne- 

 Vaughan.) 



Anatomy 

 The vascular anatomy of Loxsoma has been fully worked out by Gwynne- 

 Vaughan {Ann. of Bat. xv. p. 71). The rhizome contains a t}'pical solenostele 

 completely surrounding a central pith in the internodes, but opening at 

 each node by a leaf-gap to give off an undivided leaf-trace, hollowed on the 

 acroscopic side (Fig. 522). An unusual feature is the occurrence of islets of 

 parenchyma in the sclerenchymatous masses of the stem, a peculiarity shared 

 with certain species of Dicksonia. The leaf-trace flattens upwards, taking a 

 rather open curv^e with the usual adaxial hooks at the margins. It diminishes 



