Occurrence of Fuliaf/e-leaves in Kusi^us androgynus. 143 



rib ;* the fibro-vascular bundles are always arranged in one 

 plane; and the fibro-vascular elements are so disposed thai 

 the phloem is directed toioards the morpholorjical upper sur- 

 face, the xylem towards the lower : all as in the squama 

 fructifera, or in the Sciadopitys " needle." 



On the whole question, I must still adhere to the view 

 I have long held (in spite of the adverse opinion of 

 deservedly liigh authority), viz., that both the squama 

 fructifera and the Sciadopitys " needle " are cladodial ; 

 and it seems to me that the hypotheses, ligular and 

 foliar, to which I have above referred, are wholly unneces- 

 sary. 



In conclusion, I shall very briefly advert to a few 

 points connected with the structure of other parts of Ruscus 

 androgynus which seem worthy of notice. 



1. The aerial stem. — This affords a very beautiful and 

 typical example of Monocotyledonous structure. As in 

 most climbing plants, the xylem ducts are of large size. 



2. The roots. — These vary considerably in tliickness, 

 and are very sparingly branched. The stronger ones 

 measure from I to i of an inch in diameter. Externally 

 we have the Epidermis, numerous cells of which are 

 prolonged on their free surface into unicellular root-hairs. 

 Subjacent to the epidermis, there is a moderately developed 

 Corky Layer, some four or five cells thick. Then we come 

 to the Corticcd Parenchyma proper, which forms a zone of 

 considerable thickness (from ^^ to j\ of an inch), the cells 

 of which exhibit a certain amount of coUenchymatous 

 thickening, especially at their angles. The innermost 

 portion of the cortex is dilYerentiated to form the Endo- 

 dermis, or sheath of the vascular cylinder. The endodermis, 

 in this plant, is very remarkable. Instead of the ordinary 

 single layer, it consists of at least two, and sometimes of 

 three layers of cells, with the characteristic U-like thicken- 



* The diversity in the venation of the chiclodes exhibited by Ruscits and 

 31yrsi2)hyUi(m caimot fail to strike the observer. It is referred to by Clos 

 ("Cladodes et axes ailes," Menioircs de VAcad. de Toulouse, 5" .Ser., t. v., 

 1861), as follows : — "Les cladoJes cnrvinervcs et steviles du Daniic [Ruscus 

 racemosiis] et des M)jrsi2}?iylh(iii ont toutes leiirs uervures seniblables et de 

 meme grosseur, tandis que les orgaues de m^ie nom ont clicz les Jhiscus 

 aculcatus et Ix. Hypofjlossuni leur nervure nu'diane (florifere), et chez le R. 

 androgynus L. (Scmelc androgyna Kth.) les deux nervures laterales (florifercs) 

 beaueoup plus prononuces que les autres." 



