47 

 ON TRITHURIA F1LAMENTOSA. 



By L. Rodway. 

 Bead August 2, 1897. 



The genus Trithuria lias hitherto been represented by one 

 species only. Like the order to which it belongs, it is pro- 

 bably the remnant of an ancient stock that nourished in past 

 ages. It can hardly be said that the type is being extermi- 

 nated, in the struggle for existence its peculiar locality is 

 hardly otherwise occupied, it seems rather to be dving out 

 from some more obscure cause, a senility that renders it 

 unable to adapt itself to small, gradual change. 



All Centrolepidse of the present day are small and 

 herbaceous. The characteristic pistal remains soft, and the 

 seeds are not clearly distinguishable from those of ad- 

 joining orders, so there is little hope that we shall ever trace 

 their ancestors in leaf-beds. But their geographical distribu- 

 tion, confined as it is to regions supporting an ancient 

 terrestrial flora, and the small number of species, together 

 with their clear differentiation from adjoining types, mark 

 them as ancient survivors rather than recent productions. 



The genus Trithuria itself is of exceptional interest, in so 

 far that the ovulary has somewhat the form of that organ in 

 the neighbouring order Restiaceae, apparently indicating a 

 philogenetic relationship, but similarity ceases here. The 

 habits and tissues, the inflorescence and floral members have 

 a type of their own. The late Baron von Mueller, on the 

 strength of this apparent similarity of ovularies, combined 

 the two orders, but his view is not generally accepted. 



The plant to which I now refer grows in abundance in 

 pools on the mud flats at the head of the Broad River on the 

 Field Range. It is certainly very closely allied to Trithuria 

 submersa, Hook., but differs in important details from the 

 type as described and figured in Hooker's Flora Tasmanise 

 and all forms in Herb. Mueller. The erect bracts give a 

 Centrolepis-like appearance to the inflorescence, and the 

 stigmatic branches are long and numerous, forming a con- 

 spicuous pink brush when the plant is in flower. The 

 filaments also, instead of being short, are greatly lengthened, 

 so that the anthers are remotely protruding. Again, unlike 

 T. submersa, stamens are not freely interspersed amongst 

 carpels, but are absent from those flower heads which bear 

 many carpels, and where present are usually only two in 

 number and accompanied in the head by but few carpels. 

 Finally, the fruit, instead of being somewhat trigonous, is 

 elliptical or oval, with three inconspicuous ribs. 



Owing to the kindness of Mr. Leuhman I was permitted 

 to examine forms from von Mueller's collection, and amongst 



