142 The Irish Naturalist. September, 



Along with these forms, of which five or six might 

 often be seen growing intermixed, another Horsetail 

 occurred, which puzzled me a good deal, and to which, 

 in the course of several pleasant lounging days, I was 

 able to devote some attention. As typically developed, 

 it occupied the steep banks of the stream from about 

 one to three feet above summer level, extending occasion- 

 ally downward into a foot of water, and more frequently 

 upward into dry ground. Its usual growth was tall 

 (2 feet or more) and quite erect. The stem was slender, 

 unbranched in its lower half or two-thirds, with whorls 

 of simple branches above, diminishing into a long naked 

 tail. A search revealed fruiting stems. These were rare 

 — not more than one to one hundred barren ones — and 

 most of them w^ere not yet mature ; they w^ere similar 

 to the barren stems, save that they tended to be less regu- 

 larly branched, and were stouter above, where they bore 

 each a terminal cone which was disproportionally small. 

 The plant was strongly reminiscent of E. arvense on the 

 one hand, and of E. limosum fluviatile on the other. At 

 first glance, it suggested the former b^^ its slender stem 

 and its possession of just that peculiar shade of fresh rather 

 glaucous green which belongs to arvense, while it agreed 

 with liiYLOSum fluviatile in the similarit}^ of its fertile and 

 barren stems, its tall erect growth, its stem bare in the 

 low^er half, branched and lanceolate in outline in the upper 

 half, and the length of the bare " tail " above. Besides, 

 though usually bearing branches, it tended to lose them 

 when growing in or near the water, and stems could be 

 found which were quite unbranched, as in typical limositm. 

 And while its most striking difference from arvense lay in 

 the fact of the fertile and barren stems being similar, yet 

 the cones had the shape and pale yellowish colour of those 

 of arvense, not the black hue which characterizes limosum 

 and palustre, nor the ovoid shape of the former of these 

 two. The whole appearance of the plant, including the 

 rarity and poor development of the fruiting organs, 

 suggested a hybrid origin, with E. arvense and E. limosum 

 as parents, and called for more critical examination. 



A quantity of typical material — typical, that is, as 



