1030 JOTTINGS FROM BIOLOGICAL LABORATORY, SYDNEY UNIVERSITY, 



Psilotimi triquetrum is much more widely distributed tlian 

 Tnieslpteris tannensis, being found in Asia, Africa, and America, 

 as well as in the Australian colonies. 



It differs considerably in general appearance from Tmesipteris 

 owing to its shrub like habit, the absence of conspicuous leaves, 

 and the repeated branching of the erect stems. 



The rhizome is cylindrical and divides dichotomously. Its 

 surface is finely striate so as to present a scaly appearance, and 

 is covered with brown hairs. The single small central vascular 

 bundle is of cylindrical form and consists of an inner bundle of 

 scalariforra vessels, an outer layer of phloem, with bast cells and 

 sieve-tubes, enclosed in a sheath of short thin- walled parenchyma. 

 Surrounding the sheath is a layer of brown matter similar to that 

 observable in a corresponding situation in Tmesipteris, but less 

 strongly developed. It seems to be arranged in longitudinal 

 branching and anastomosing lines which are situated for the most 

 part in intercellular spaces, but seem frequently to bi'eak into the 

 cavities of cells. Outside of this is a thick zone of thin-walled 

 parenchyma. The epidermal cells present no well marked cuticle. 

 "The aerial stems are marked by a series of longitudinal ridges ; 

 of these there are, as a general rule, five in any given section of 

 the stem. These are connected with the leaves. The leaves are 

 veiy small, narrow appendages, scarcely two millemetres in length, 

 sparsely developed on the longitudinal ridges. In the case of the 

 principal branches there are only single leaves ; these are arranged 

 with tolerable regularity, a leaf to about every two inches of each 

 ridge. Where the leaf is inserted there is a notch in the ridge, 

 the latter running on undiminished in size. 



Each pair of leaves (' bracts ') with the sporangium terminates 

 one of the ridges. They are arranged with tolerable i-egularity, 

 but there seems to be no definite phyllotaxial law. At the ends 

 of the branches the leaves ai-e closer together, and the growing 

 point is surrounded by about three rudimentary leaves. The 

 •singular vascular bundle is nearly circular in transverse section, but 

 the vessels themselves are arranged in five to eight groups more or 



