1026 



caution into our gardens these plants soon dry up, in a few hours 

 they become black and so brittle that they appear to have been 

 scorched. Bearing in mind these facts, the question suggested itself, 

 whether the uncuitivable Rhinanthaceae might not be parasitic plants; 

 in fact, their rapid death in our gardens and their injurious effects 

 upon the neighbouring plants, a fact well known to cultivators, led me 

 to suspect their parasitic nature. The observation which I have the 

 honour to bring before the Academy settles this question. The spe- 

 cies of Alectorolophus, Melampyrum and Odontites are true parasitic 

 plants which fix themselves to the roots of grasses, shrubs, or even 

 trees, by numerous suckers. These suckers are arranged on the 

 branched and delicate rootlets of Melampyrum in the same manner as 

 on the filaments of Cuscuta ; the parasitic rootlets are in close contact 

 with the young roots of the plants upon which they feed ; the point 

 of contact is indicated by a swelling. 



I regret that I have not yet been able to verify the parasitic nature 

 upon other species than those which occur in our fields. I propose 

 however to examine whether what I have observed in the plants of 

 this neighbourhood will occur or not in analogous plants, or whether 

 this phenomenon is so modified in them as to afford an explanation of 

 the anomalies of structure I am about to point out. 



In a memoir* presented to the Academy, M. Duchartre described 

 in a parasitic plant, Lathraea clandestina, a peculiar ligneous structure, 

 the most prominent character of which is the absence of medullary 

 rays : on the other hand, M. Elie Brongniart in noticing this fact in his 

 report on this paper wished to ascertain whether it did not occur in 

 other plants belonging to the same class as L. clandestina, and he 

 found it in Melampyrum : nevertheless in pointing out the anomalous 

 structure in these vegetables, MM. Brongniart and Duchartre did not 

 connect it with the fact of parasitism, but merely saw in it a relation 

 of family. However, this peculiar organization appears to me inti- 

 mately connected with the parasitic nature of the plants, judging 

 from the uniformity of structure and the black colour of the stems of 

 Pedicularis, Castilleja, Cymbaria, Bartsia, Buchnera, which are all 

 destitute, according to my observations, of medullary rays. 



If parasitic plants assume a black tint mixed with blue on drying 

 — if the absence of medullary rays is one of their attributes — and if 

 these characters are connected with a special absorption of the nutri- 

 tive juices, I may observe that these occur without exception in a 



* A Uanslation of this memoir appeared in the ' Annals ' for June, 1845. 



