BOTANICAL GAZETTE. 



Vol. IV. DECEMBER, 1879. No. 12. 



DiMORPHO-DicHOGAMY IN JuGLANS ciNEREA, L. — All the trees of tliis 

 species which have come under my observation range themselves 

 clearly into two distinct sets as respects the relative development of 

 their sexual organs. In one set the stamens mature some ten days 

 in advance of the jiistils on the same trees. In the other set, how- 

 ever, they are at this time just ready to receive pollen, while the 

 stamens which accompany them only develop and shed their pollen 

 in time to fertilize the pistils of the set first mentioned. This simply 

 is the monoecism of the species carried one step further, and self- 

 fertilization becomes scarcely possible. 



As respects the bearings of this arrangement on the fertility of the 

 plant it is obvious that isolated trees, or those otherwise unfavorably 

 located with respect to their fellows, must be liable to sterility; and, 

 likewise, that weather favorable or unfavorable to the transmission 

 of pollen by the wind, or to the operations of insects among the 

 Howers, prevailing earlier or later, when either corresponding set of 

 sexual organs is at full development, must lor that year intluence the 

 fertility of one half the trees. 



It is desirable that some one favorably located will observe the 

 behavior of the other species in this regard. Our species of Carija, 

 also, need attention, ior I have seen in this genus at least a dispo- 

 sition to assume the same arrangement. — C. G. Pringle. 



Leaf-propagation of Nasturtium lacustre, Gr. — Earlv in Julv 

 this plant, then coming into flower, begins to cast its leaves, com- 

 mencing with the lowest and most dissected and progressing upward 

 along the stem even to the small entire ones on the branches. They 

 fall not in the least withered or faded with age, but while still green 

 and gorged with elaborated material for growth, as soon, in short, as 

 they have attained their fullest development. Alighted on the sur 

 face of the soft mud or ooze, which is the habitat of this species, 

 each leaf puts forth from a minute bud at its extreme base a young 

 plant which develops stem and leaves simultaneously with roots, ab- 

 sorbing and appropriating the nutriment stored in the leaf, whose 

 frame in a short time decays, while the plantlet goes on in an inde- 



