EXPEKDIENT STATION IJill'Oiri'. 503 



There are some membcrr^ of the saiiu' i,n-()U|) of ])laiils lliat pciu'trate 

 the tissue ol living plants, and tlu're propagate as parasites, and often 

 prodnt-e nialforniations in tlir host. Of siuii arc tli.' cluli-rooi of tli<- 

 eabbage, turnip and allii'd plants, and often l)eeoinf quite destructive 

 to crop plants. This sul)ject has been considered at length, and the 

 results have appeared in previous annual reports and Bulletin i)8* 

 of this departr^ient. 



A somewhat similar <pccies of slime-mold has been demonstrated 

 by Professor Tourney fa< causing the grown-gall upon peach, almond 

 apple and other orchard fruit trees, and to which he gav.- the botanical 

 name of D<'ndrophagus ghbosiis Tou. 



A second species of slime-mold that has been sent to tlie lv\i)eriment 

 Station is shown in Plate X. (right hand). This was also sent to Dr. 

 !MacBride, who determined it to be Fhysamm cinercum Batsch., and of 

 it he writes: "It occurs not infrequently on the leaves, stems and 

 flowers of various herbaceous plants, l)y no means infrequentlv liere 

 [Iowa] on the leaves, etc., of strawberry plants. I suppose it linds 

 sustenance on the decayed organic matter offered in the way of 

 nuinure, and in this way only can it effect the welfare of the cdli- 

 vated plant."' The delicate nature of this mold can scarcely be shown 

 in the photo-engraving, but something of tlie ashen-gray spore sacs 

 can be seen covering the veins of the leaf. 



Broom-Rape, a 'Weed Upon Greenhouse Tomatoev. 



During last winter, or, more accurately, in the early spring, the 

 experiment tomatoes in the greenhouse became seriously affected with 

 the broom-rape {Orobanche ramosa L.). Some of the ttmiato plants 

 had a yellow, sickly appearance some time before the parasite pushed 

 its dark-olive tips above ground, and by the time the broom-ra})e was 

 in full bloom the supporting tomato plant had ceased to grow, and, 

 of course, did not mature any fruit. So alnmdant was this jiarasitic 

 plant that it materially interfered with the e.\|)<^riments and was 

 therefore, even though handsome and interestingly ])L'culiar. a real 

 greenhouse weed of the sort that is not easy to keep from doing in- 

 jury, because its work is much under the cover of the soil. 



* Club-Root of Cabbage and Its Allies, December 9th, 1893. 



t An Inquiry Into the Canse and Nature of the Crown-Gall, J. W. Toumey, Bul- 

 letin 33, Arizona Experiment Station, April 13th, 1900. 



