24 ENGLISH BOTANY. 



primary meshes do not (or but rarely) contain secondary veins. The 

 cells of the epidermis are separated by straight boundary lines, while 

 in 0. vulgatum the boundaries of the cells are sinuous. The spike 

 contains fewer sporangia in each row ; in the Guernsey plant they 

 are three to six on each side ; but I have Continental specimens with 

 as many as ten in the row, and Milde says there are sometimes nine- 

 teen. The sporangia do not extend so near the apex of the spike as 

 in 0. vulgatum, the bare part extending like a little point or spur 

 beyond the fertile part and bearing a much greater proportion to the 

 length of the spike than in 0. vulgatum. The spores are consider- 

 ably smaller than in 0. vulgatum, and are quite smooth. 



Dwarf Adders-tongue. 



GENUS II.— B OTRYOHIUM. Schwartz. 



Herbs with the caudex not tuber-like, passing downwards into a 

 slender creeping branched root. Frond produced within the base of 

 the stalk of that of the preceding year. Barren branch of the frond 

 varying from oblong and pinnate or even only pinnatifid to deltoid and 

 ternately decompound ; fertile branch stalked or subsessile, once to 

 3 or 4 times compound, oblong- triangular or deltoid, nearly all in 

 one plane or incurved. Sporangia free, disposed in a distichous 

 compound or decompound spike. 



Name from /3oTpvs (botrus), a bunch of grapes, from the appearance of the fertile 

 branch of the frond. 



SPECIES I.— B OTRYOHIUM LUNARIA. Schwartz. 



Plate 1837. 



Babenh. Crypt. Vase. Europ. Exsicc. No. 9. 



B. lunatum, Gray, Nat. Arr. Brit. Plants, Vol. II. p. 19. 



Osmunda Lunaria, Linn. Spec. Plant, p. 1519. Sm. Erig. Bot. ed. i. No. 318. 



Base of the frond without a slit on one side where it encloses the 

 bud that forms the frond of the succeeding year. Sterile segment of 

 the frond placed about the middle or above the middle of the whole 

 frond, sessile, oblong or ovate-oblong, pinnate; terminal segment 

 truncate and incised at the apex ; pinnae lunate or fan-shaped, entire 

 or crenate, or more rarely incised at the apex, without a midrib ; 

 veins radiating from the base, repeatedly forked, not extending quite 

 to the margin ; cells of the epidermis straight-sided. Fertile branch 

 of the frond conspicuously stalked ; stalk often exceeding the length 



