EXPERIMENT STATION EEPOET. 509 



A number of crosses were probably obtained between various varie- 

 ties or species of ornamental plants. This portion of the work is an 

 aside, although one that may be as important as it is interesting. 



BROOM-RAPE UPON PELARGONIUM. 



The common "geranium" (pelargonium) is quite immune to attacks 

 of the lower forms of parasite, and insects are not troublesome upon 

 this truly popular ornamental plant, whether in the foliage and flower 

 l)eds in summer or in the window and conservatory in winter. It is a 

 matter for record, therefore, that among the few plants grown in the 

 greenhouse last winter one should have been attacked by a broom-rape, 

 which, when it had attained its full size, was larger than the "gera- 

 nium" upon which it grew. It is the species known as Orobanche 

 minor J. Esm, and has for its more general hosts the members of the 

 pea family, and in this locality is frequently met with upon the red 

 clover. Plate XY. shows some of the peculiarities of this parasite, 

 including its attachment to the geranium plant. 



The seed of this parasite germinates in the soil and the young roots 

 attach themselves to- those of the "geranium," after which it seeds 

 up above ground a purplish, erect stem, bearing small, scale-like leaves 

 of the same color, and later on a number of blooms scattered quite 

 uniformly along the unbranched stem. The absence of green in the 

 sun-exposed parts marks this plant as a parasite, and a close inspection 

 of the roots shows that it gets its nourishment from another plant of 

 the ordinary self-supporting type. In the present instance the "gera- 

 nium" cuttings failed to flourish, and the cause of the sickly appear- 

 ance was not far to seek so soon as the parasite pushed its stems above 

 the ground, which resembled the tips of young asparagus shoots as 

 they came through the soil, although the broom-rape is somewhat 

 smaller. 



There is one other broom-rape that has been in evidence in the 

 greenhouse, namely, the Orobanche ramosa L., the hemp broom-rape, 

 which grows to some extent upon the tomato plants — in fact, there 

 were specimens of the two species in sight at the same time, and had 

 there been the desire a ^lybrid possibly might have been secured be- 

 tween the two, with results as to the relation to host plants that are 

 left for the imagination to supply. 



