146 The Irish Naturalist. September, 



form ; and while the collected specimens figured in the 

 Journal of Botany, approach the former condition, 

 garden-grown specimens in my own and other herbaria 

 supplied by Mr. Arthur Bennett, are as much branched 

 as ordinary arvense. The Hilltown plant belongs to Milde's 

 var. elatius, characterized as follows : — " Caulis erectus 

 2-4' altus, apice longe attenuatus, superne et inferne nudus, 

 medio verticillis densis ramorum vestitis ; rami superne 

 sensim decrescent es, unde caulis imaginem caudae longae 

 referens. Spica procaulelongoparva/' (Milde, /. c. p. 365). 

 i\Iilde records this variety from Schlesien and Provence, 

 and characteristic examples of the Hilltown E. litorale are 

 identical wdth specimens from Aries, collected by Duval- 

 Jouve, in the Kew Herbarium. It may be noted that 

 where at one place the Hilltown plant descended into the 

 stony stream-bed it assumed the gracile form, becoming 

 smaller, slender, and quite unbranched. 



The parentage E. palnstre x Umosum has been suggested 

 by some writers for E. litorale, and W. H. Beeby, in discussing 

 the English plant (/. c.) follows Nyman in adopting this 

 view ; but the Irish plant, if a hybrid at all, has certainly 

 arvense, not palnstre, as one of its progenitors. As regards 

 the other parent, the absence of the ring of thickened cells 

 in the cortical tissue clearly indicates Umosum, as this 

 character is not found in any other species of Horsetail. 



In the preceding paragraphs, I have described the steps 

 by which this critical plant was identified, rather than 

 merely publish the record of its occurrence, in the hope that 

 Irish botanists wall examine local Horsetails with a view 

 to extending the range of so rare a plant, and that they wdll 

 be assisted by the comparative notes w^hich I have given. 

 The botanist visiting the Mourne Mountains will find 

 E. litorale growing along the Rocky River for about a mile, 

 from the point where it is joined b}^ Shanky's River 

 (ascending the latter stream for a short distance) down 

 to the old mill-dam above the junction of the Rocky River 

 and the Bann. It is likely to occur elsewhere, and if 

 fruiting cannot be mistaken ; when not fruiting, the best 

 characters are the number of teeth (intermediate between 

 the number in arvense and Umosum) and the size of the 



