1025 



inches in length. The frond a appears as when the plant was receiv- 

 ed two years and a half since, discoloured at its extremities : with 

 these exceptions, none of the fronds, now eleven in number, exhibit 

 any symptoms of decay. There is no appearance of fructification. 

 From these records, trivial as they may appear to some, the endur- 

 ing nature of the fronds of Trichomanes is established : the peculi- 

 arity may be due in some measure to the treatment, but I believe it 

 is mainly attributable to an innate character of the plant, which is 

 thus truly entitled to the epithet of evergreen. 



Edward Newman. 



October 28, 1847. 



Observations on the Parasitical Nature of the Wiinanthacea, in 

 reference to Mr. Mitten's paper on Thesium linopliyllum 

 (Phytol. ii. 807). By J. Decaisne. Extracted from the 

 'Comptes Rendus' for July, 1847, as translated in the 'Annals 

 and Magazine of Natural History ' for September. 



Since De Candolle established by ingenious observations and accre- 

 dited by the authority of his name the separation of parasitic plants 

 into two groups, physiologists have generally admitted it as a well- 

 established law. It is known in fact that the phanerogamous plants 

 which are parasitic upon the stems of other vegetables have green 

 leaves, while those upon roots do not possess true leaves, contain no 

 green colouring matter, but are generally of a whitish, yellowish or 

 violet colour; in other words, they appear blanched or sickly when 

 compared to other plants : their leaves, or the scales with which their 

 stems are provided, are generally without epidermic pores. The ab- 

 solute character of the law advanced by De Candolle has however 

 been recently modified by the observation of Mr. W. Mitten [Phytol. 

 ii. 807] of a plant (Thesium linophyllum) parasitic upon roots and 

 nevertheless provided with green leaves. 



The observation of Mr. Mitten immediately called to mind a fact 

 I had long noticed, that is, the impossibility of cultivating plants be- 

 longing to the group of the true Rhinanthaceae. Wishing to intro- 

 duce into cultivation the purple cow-wheat {Melampyrum arvense), I 

 fi-equently sowed the seed, which however all perished a few days 

 after their germination without my being able to account for this want 

 of success. The same applies to species of Pedicularis and Euphrasia: 

 removed with care fi'om the field and transferred with every possible 



