J ^9-] BOTANICAL GAZETTE. 



35 



the tissues of the first ; this inter-parasitism also occurs fre- 

 quently when for a long distance stems intertwine. 



There is little dilt'erentation in the tissues of the dodder; 



it needs, very early, conducting tissue for carrying moisture 

 through the stem to the rapidly growing and probably assimi- 

 lating apex. To meet this need vascular tissue is found a 

 soon as germination takes place. It is very simple, consist- 

 ing of alternate stripes ot tracheids and parenchyma, each 

 about two rows of cells broad, and in the best developed stem- 

 occupies perhaps from one-third to one-half the diameter. 

 It is well adapted for twining by this alternation with the 

 softer parts, while the predominance of the latter favors the 

 carrying of elaborated material, as it is in these such pro- 

 ducts travel. Iodine testities to the presence of starch in the 

 tissues of mature plants. Other reagents show, as do the 

 markings on the walls, the woody nature of the alternate 

 bands evident in a section of stem. 



Of the adventitious buds, known to be abundant in the 

 dodders, I h ive studied only those producing branches. 



Their origin was in this manner: When a parasitic root 

 had become well established, so that the plant was thoroughly 

 engrafted upon the host, in an axil thus formed, a branch 

 would arise, after the manner of an axillary branch on a 

 normal plant. The regular branching of a stem of Cuscuta 

 is unusual in the centrifugal ly arranged accessory buds (figs. 

 6 and 7), the last formed bud being farthest from the 

 parent stem, though sections show it to originate in the axil 

 bundle. 



The epidermis of dodder varies with its position. On the 

 long internodes between adjacent scales stomata are rare, 

 while oyer suckers, /. e., on the side of the stem opposite 

 them, very small stomata are quite abundant. This explains. 

 in a measure, the continuance of life and growth for two 

 weeks or more in branches cut from the parent stem and 

 suspended in the air, though such stems never form coils or 

 suckers. 



Each flower has a short pedicel like the main stem in 

 structure, a thickened receptacle, a five-lobed calyx and cor- 

 olla with beautifully branched fringes lining the latter, and 

 adherent stamens alternating with its lobes : the ovary has 

 two cells with two ovules in a cell, and there are two knob- 

 like stigmas on short styles. As to the manner of fertiliza- 

 tion of the dodder, whether self or cross fertilized, I have 

 had no opportunity to observe. 



