A Note on the Vegetative Anatomy of Pherosphaera 
Fitzgeraldi, F. v. M. 
BY 
PERCY GROOM, M.A., D.Sc., 
Professor of the Technology of Woods and Fibres , Ini ferial College , London. 
With one Figure in the Text. 
HEROSPHAERA is a coniferous genus separated by Archer from 
1 Dacrydium , but by some botanists placed within this genus. It 
includes only two species, both Australian— P. hookeriana , Archer, restricted 
to alpine Tasmania, and P . Fitzgeraldi , F. v. M., only known to occur on 
the Blue Mountains of New South Wales. 
The latter species is a dense, prostrate little shrub, whose slender 
twigs are clothed with numerous narrow, keeled, leaves, which are about 
3 mm. in length. In their book ‘ The Pines of Australia Baker and 
Smith state that the plant is ‘ found at the base of most of the chief falls 
and add that their material (used in the present investigation) was obtained 
at the Lower Falls, Leura, in which site the shrub ‘ only grows where it can 
catch the drips from the falls ’. 
The remarkable nature of the habitat, recalling that of certain 
Hymenophyllaceae in tropical forests, caused me to examine the structure 
of the wood and leaves, in the hope of discovering a conifer truly hygro- 
phytic in structure. 
a. The Wood. 
In its construction the wood of the stem by no means suggests 
a hygrophyte. In the thickest stem available the diameter was 4*5 mm., 
yet the number of annual rings present was thirteen. The radial thickness 
of each annual ring was therefore 0*173 mm., and thus represented 144 
annual rings to the inch radius. The thickness of the annual rings increased 
outwards from the first to the tenth, but decreased in the remaining three 
rings ; it is therefore probable that the stem had passed its maximum rate 
of growth in radial thickness. 
All the tracheides of the secondary wood are thick-walled, and recall 
those forming the summer-wood (autumn-wood) of such a conifer as Pinus 
[Annals of Botany, Vol. XXX. No. CXVIII. April, 1916.] 
