A CONTRIBUTION TO THE PARASITISM OF NOTOIHIXOS INCANUS 

 (OLIV.). VAR. SUB AUREUS. 



By J. McLucKiE, M.A., D.Sc, Lecturer in Plant Physiology, The University of 

 Sydney. 



(Eleven Text-flgui'es.) 



[Read 29th November, 1922.] 



Notothixos incanus (Oliv.) var. subaureus is a parasite which frequently oc- 

 curs upon species of Loranthns, especially L. celastroides, L. pendulum and L. 

 eucalyptifoliiis, in New South Wales. I have also found it growing upon the 

 branches of Phyllanthus, Eucalyptus corymhosa, Angophora lanceolata, and 

 several species of Casuarina. It branches dichotomously, and its young shoots 

 and leaves are covered by a thick tomentum of golden-yellow, multicellular, 

 branched haii-s. The flowers are usually sessile, and occur in small pedunculate 

 inflorescences. The fruit is sligiitly succulent and tomentose, and contains a 

 single gelatinous-eoated seed. The parasite is distributed over the eastern portion 

 of the State, extending from the Coast District to the Blue Mountain Plateau, 

 and requires moist climatic conditions during dissemination and germination. 

 Dissemination. 



Notothixos incanus (Oliv.) var. subaureus flowers in May- June and the 

 fruits ripen about twelve months later. They are small, practically oval in 

 shape, covered with multicellular, yellowish, branched hairs, and are not ex- 

 plosive as in Arceuthobium occidentale (Pierce, 1905) ; the seeds are extruded 

 by a gelatinous tissue within the fruit. 



Dissemination takes place during moist, humid weather when there is little 

 evaporation from the surface of the leaves. Under such conditions the fruits 

 become exceedingly turgid, owing to certain gelatinous tissues swelling, and a 

 slight movement of the branches or shock, causes the fruit to drop oS, and the 

 seed to glide out. 



Text-fig-ure 1 shows a longitudinal section of a mature fruit containing one 

 seed. The fruit is attached to a short stalk from which it is readily parted 

 when ripe. Externally the fruit is covered by a heavily cutinised epidermis (ep). 

 one layer of cells in thickness, and with the outer walls considerably thickened. 

 Stomata with depressed giiard-cells are present; numerous yellowish-coloured, 

 multicellular, branched hairs are developed over the surface of the fruit. 



