208 
HISTOHY OF BRITISH FERNS. 
derived from the Greek o^pTiis^ opMos, a serpent, and glossa, 
a tongue ; and is applied in consequence of the resemblance 
of the fertile fronds to the tongue of a serpent. 
Ophioglossum vulgatum, Linnceus, 
The Common Adders-tongue. (Plate XVIIL fig. 3.) 
A small stemless plant, producing a few coarse brittle 
roots from a central crown which represents the stem, and 
which annually produces a bud from which the new frond 
arises. The young fronds are produced about May, and 
perish by the end of the summer. They grow from six 
inches to ten or twelve inches in height, with a smooth, 
round, hollow, succulent stipes of variable length. In the 
upper part this becomes divided into two branches, the one 
branch leafy, entire, smooth, ovate-obtuse, traversed by 
irregularly anastomosing veins, forming elongated meshes 
within which are free divaricating veinlets. The fertile 
branch is erect, contracted about half its length, being 
soriferous, forming a linear slightly tapering spike, which 
consists of two lines of crowded spore-cases imbedded in 
the substance of the spike, and occupying its two opposite 
sides. The spore-cases are, therefore, considered as being 
produced on the margins of a contracted frond. When 
