The Anatomy of Nephrolepis volubilis J.Sm. 261 
towards apex, a is at the extreme base, e very near the apex. Xylem shaded, 
protoxylcm solid black, phloem within the continuous line, endodermis , a broken 
line. 
The petiolar structure was described for Nephrolepis in general 
terms by Trecul 1 long ago, though no figures were given. These may 
now be given for N. volubilis (PI. 4, fig. 3; Text-fig. 6). Immediately 
before the three leaf-trace strands enter the petiole, the dorsal 
anastomoses with one of the vento-laterals (a) but it soon becomes 
free again. The petiole at this stage is circular in section. The 
usual adaxial groove soon appears on it, and at the same time the 
outline of the xylem portion of each strand, nearly circular at first, 
becomes crescentic in the manner shown ( b ) the positions of the 
protoxylems being indicated in solid black, while the metaxylem is 
shaded. Phloem completely surrounds the xylem, being particularly 
abundant in the deep bays at the outer side of each ventro-lateral 
strand. The strands to the pinnae are given off from the adaxial 
horn of each crescent ( c ). The dorsal strand, passing up through 
the long rachis, anastomoses alternately with the two ventro-laterals 
twice or thrice with each. Ultimately, however, it loses itself into 
one of them ( d-e ). Meanwhile, the latter approach each other ( c ) 
by their convex sides and fuse along the middle-line, forming the T 
already mentioned by Trdcul ( e ). 
The stage e deserves notice on account of its similarity to a 
transverse section of the petiole of Lygodiumjaponicum. As in that 
Trecul, Ann. Sci. Nat. V, t. 10, 1869, pp. 351-2. 
1 
