332 M. A. Chatin on the Anatomy of the Rhinanthacese. 



Related to the OrobanchecB by their rhizome with wide me- 

 dullary communications, by their epidermis with subhexagonal 

 cells containing oleo-resinous drops, by their squamiform leaves 

 with a homogeneous parenchyma, and the vessels crowded into 

 a bundle in the axis of the nervures, the Epirhizanthacea ap- 

 proach very closely to the Rhinanthacea by the similarity of the 

 vessels and fibres in the stem and rhizome. 



To the morphological differences, considerable as they are, 

 which separate the Rhinanthacea from the Orobanchea, we have 

 to add some anatomical facts, which acquire great value from 

 their constancy and general occurrence : such are the rhizome, 

 constantly destitute of medullary rays, and with its vessels never 

 grouped ; the stem with a scattered vascular system and a di- 

 stinct medullary sheath ; the leaves with numerous stomata, with 

 green matter, with the parenchyma sometimes heterogeneous, 

 and the vessels distinct from one another. 



The OrobanchecB have numerous morphological affinities with 

 the Rhinanthacea, which would be sought for in vain between 

 them and the Monotropea ; but nevertheless it is with the latter, 

 which, like them, are more completely parasitic than the Rhi7i- 

 anthacea, that they present the greatest number of anatomical 

 relations ; so true is it that the structure of organized beings 

 stands in necessary relations with their mode of life. 



Each of the genera of the Rhinanthacetz has its anatomical, 

 as well as its floral characters. Castilleja, like Obolaria, has the 

 medullary sheath scarcely, if at all, distinct ; but its stem is pro- 

 vided with a fibro-cortical ring, and often with feculiferous fibre- 

 cells. Schalbea differs from Castilleja by its vessels arranged 

 in radiating lines in the stem, and by its irregularly folded 

 epidermic cells. The Bartsice are destitute of the fibro-cortical 

 system, and have the medullary sheath distinct. Odontites and 

 Euphrasia, which have but little morphological distinction, are 

 confounded by their anatomy. Cymbaria is well characterized 

 by its vessels being frequently approximated by twos and threes 

 in the rhizome, and all placed in radiating lines in the stem, by 

 its fibro-cortical layer, and by its thick pitted fibres which 

 enter into the bundles of the leaves. Rhynchocorys, recently 

 separated from Rhinanthus by the morphologists, is a genua 

 which is admitted by anatomy, as the spiral vessels of the 

 sheath are not arranged upon the lines of the pitted rayed 

 vessels of the woody layer, and as in the leaves the vessels are 

 isolated from each other, at the same time that the parenchyma 

 is homogeneous throughout its thickness. Pedicularis, a nume- 

 rous genus, the species of which present considerable floral 

 difi'ereuces, exhibits no more uniformity in its anatomy than in 

 its morphology. We may, however, regard as its general cha- 



