BOTANICAL GAZETTE. 



2R1 



The foliar noctar glands ofPopiilns: by Wm. Treleasc — 



Early in May, t8So, my attention was drawn to a small nsi)en (/'. 

 trciiiuloidcs) by the actions of several green bees, belonging to the 

 species known as Auf;oc/i/ora pura. At this time the tree was covered 

 with newly expanded foliage; and the bees, flying busily from leaf t« 



leaf, were evidently at 

 tracted by something and 

 a moment's observation 

 Ml sufficed to show that they 



were engaged in collect- 

 ing nectar, secreted by a 

 double gland at the base 

 of each leaf. Theseglands 

 were placed on the uj)- 

 per surface of the petiole 

 (Fig. 6) at its union with 

 the blade, appearing, in- 

 deed, almost as if the 

 petiole projecting above 

 the upper surface of the 

 blade had been abruiJtly 

 cut down to the level of 

 the latter, the truncated 

 end being the secreting 

 portion of the g'and. 

 Longitudinal sections of 

 the glands showed them 

 to have the structure us- 

 ually found in members 

 of the sort : the epidermis 

 was transformed into a 

 double layer of thin- 

 walled elongated cells, 

 forming the secreting sur- 

 face just mentioned ; and 

 these cells, as well as the 

 subjacent parenchyma, were charged with saccharine fluids. The 

 homology of the glands, however, was not so readily determined. 

 Each was more or less deeply bilobed and plainly consisted of two 

 confluent glands, and from their similarity, in point of situation, to the 



Explanation of fkuiurs.— Fig. 1. Quadrifid gland from base of loaf of 

 r^ypnhiK tremulii, vur. peiuli/la, enlarged. 



Fig. 2. Glands from the sumo plant, borne upon the leaf-margin, enlarged. 



Fig. 8. Branched glands from P. moiiiliferd, enlar,u;ed. 



Fig. 4. Base of leat of P. momlifei'it having one glaiid displaced and borne 

 on the margin, enlarged. 



Fig. 5. Base of loaf of y\ ^/•iV7ww//'Drt, showing the gradation ofpeliolar 

 into serration glands, natural size. 



Fig. 0. Leaf of /'. //rw;*//«?V/cs, showinii- the ordinar}- form of lli<' double 

 gland, natural size. 



