APPENDIX. 



469 



PARENCHYMA 

 \ 



BUNDLES 



/ 



/ SCLERENCHYMA 



PERIPH. SCLERENCHYMA 



Fig. 8. Rhizome of Bracken. 

 (Diagrammatic transverse section.) 



for the whole shoot, or leafy stem. The real stem, or 

 rhizome, creeps underground, often more than a foot deep, 

 and is very different from 

 that of the Male Fern. It 

 burrows along horizontally 

 in the soil, giving off roots 

 all over its surface and only 

 sending up the large com- 

 pound leaves here and there. 

 Dig up a whole plant and 

 examine the stem. Note the 

 withered bases of the leaves 

 of former years, and the 

 young leaves for next year. 

 The latter are small knobs, 

 covered with brown scales. 

 The stem usually branches 

 once a year, and the grow- 

 ing tips of the branches are 



covered with scales like those on the young leaves. Each 

 branch, as a rule, produces only one leaf each year, and the 



leaves are spaced out on 

 the stem and arranged 

 in two rows, right and 

 left. The stem is black 

 in the older parts, except 

 for two lighter lines 

 which run along each 

 flank. 



On cutting across the 

 stem, note the hard 

 blackish band of fibrous 

 tissue which surrounds 

 it except at the light 

 lines just mentioned ; 

 these light lines, where 

 the soft whitish ground 

 tissue is exposed at the 

 surface, probably serve for exchanges of gases and may be 

 compared with the lenticels on woody stems. The ground 

 tissue is traversed by dark-coloured bands, consisting of 



~-INDUSIUM 



PARAPHYSES 

 'SPORANGIA 



PLACENTA 

 "FALSE INDUSIUM 



.,SORUS 



Fig. 9. Sporangia of Bracken. 



A, Two fertile pinnules ; B, Transverse section 



of pinnule. 



