Plate 65. 
EQUISETTJM trachyodon, A. Braun. 
Bough-toothed Horsetail. 
Equisetum (§ Hyemalia) trachyodon; stems branched at the base; branches 
long, flexuose, simple, or again irregularly-branched towards the apex, very 
scabrous, furrowed; sheaths ultimately wholly black, with six to thirteen 
narrow, somewhat persistent, subulate teeth; catkins terminal, mucronate. 
Equisetum trachyodon. Al. Braun , Regensb. Bot. Zeit. v. 22. p. 308. Koch, 
Syn. FI. Germ. ed. 2. v. 2. p. 967. Duval-Jouve, in Bull. Soc. Bot. v. 5. 
p. 518./. 8. Bab. Man. Brit. FI. ed. 4. p. 416. Hook, and Am. Brit. 
FI. ed. 8. p. 601. 
Equisetum Mackaii. Newm. Brit. Ferns, p. 25 (with figure'). Hook, and Am. 
Brit. FI. ed. 7 and 8. 
Equisetum elongatum. Hook. Brit. FI. ed. 5, vix Willd. 
Hab. Colin Glen, Belfast, Mackay and Whitla; north of Ireland, in many of 
the glens, C. Moore; banks and inundated portions of banks in the bed of 
the Dee, Aberdeenshire, Mrs. Brichan. 
i 
When my attention was first directed to this Equisetum by 
Messrs. Whitla and Mackay, I was disposed to refer it, but as 
it appears without sufficient reason, to the little-known E. 
elongatum of Willdenow, I afterwards acquiesced in calling it 
E. Mackaii of Newman; and now I believe that Mr. Babington 
has satisfactorily shown it to be the E. trachyodon of Alexander 
Braun. Still I feel doubtful as to its being a permanently dis¬ 
tinct species. It evidently belongs to the same group or division 
of Equisetum as E. hyemale , and one might almost look upon it 
as holding an intermediate place betw T een that and the following 
species, E. variegatum; indeed, Koch (a very careful observer) 
remarks, 1. c., “ Sequente ( E . varieg.) triplo crassius, pars mem- 
branacea, dentibus vaginarum imposita, subulata ex ovato- 
lanceolata basi, in dorso et margine muriculato-scabra, albida 
linea dorsali fusca, in apicem excurrente.” These marks are 
almost too minute to be practically useful. The same may be 
said of the lacunes seen under the microscope in the transverse 
sections of the stem, on which M. Duval-Jouve places great re¬ 
liance. It is recorded as a native of Germany, and has pro¬ 
bably been overlooked elsewhere as some other known species; 
