The Histology and Development of Cassytha 

 Filiformis, L. 



(.WITH PLATES XXXIII, XXIV.) 



By Harriet Boewig, B. S. 



The order Lauraceae is composed of green shrubs or 

 trees of independent growth and normal nutritive relations, 

 excepting in the genus Cassytha, which is unique in the 

 extremely reduced condition of its vegetative system and 

 in its parasitic habit. The latter peculiarity has attracted 

 the attention of several observers, who have carefully investi- 

 gated the relation of the plant to its host. Comparatively 

 little has been done to the histology, and apparently no effort 

 made to trace the relation of the seed to the adult. 



It was mainly to complete the gaps in the history of this 

 interesting genus that the present paper was undertaken, 

 under the guidance of Professor Macfarlane, to whom I take 

 this opportunity of expressing my indebtedness for the kind 

 assistance he has at all times rendered me. The material 

 for study was collected by him during the University's expe- 

 dition to Florida in December and January, 1 900-1 901 ; and 

 from fruits collected on the spot, seedlings have grown suc- 

 cessfully in the University greenhouses. 



The genus Cassytha is worldwide in its distribution in the 

 tropics and sub-tropics. In habit it much resembles the 

 stronger of our native Dodders, clambering over bushes so 

 as to form masses several yards across. The color in hot, 

 sunny exposures, as with Cuscuta Gronovii, is pale tawny 

 yellow, but in shaded places it is of a rich dark green hue. 

 All intermediate gradations were seen. The same plant on 

 sunny and shady sides shows these differences most mark- 

 edly. 



{399) 



