372 



BOTANY. 



490. The Filicinae may be here arranged under four 



orders, as follows :* 

 /. IsosporecB. 

 Spores of one 

 kind. 



Order 1. Pilices, 

 the true Ferns. 



Pig. 256. Prothallium and you 

 antum CapUlus-Veneris, seen in v 

 section. p,p, the prothallium ; a, archegonia : A, root- 

 hair ; E, the young plant ; u\ its first root ; b, its first 

 leaf, x about 10. After Sachs. 



Sporangia compos- 

 longitudinal ed of modified tri- 



ehoroes, each de- 

 veloped from a sin- 



gle epidermal cell, produced in clusters on the surface of or- 

 dinary or slightly modified 

 leaves. Each sporangium 

 with an elastic ring. No stip- 

 ules. 



Order 2. Marattiaceae, the 

 Ringless Ferns. Sporangia 

 produced from a group of epi- 

 dermal cells ; the ring either 

 rudimentary or wanting. The 

 large, much - branched leaves 

 with stipules. 



Order 3. Ophioglossacese, 

 the Adder-Tongues. Sporan- 

 gia formed by groups of cells 

 in the interior of a modified 

 branch of the sheathing leaf. 

 The ring is absent. 



//. Heterosporece. Spores 

 of two kinds. 



Order 4. Rhizocarpeee, the 

 Pepperworts. Sporangia com- 

 posed of modified trich- 

 omes (?); the microsporangia 

 containing many microspores, ne of the stem.-After Sachs.' 



* This arrangement is essentially that modification of Sachs' pro- 

 posed by Professor McNab. See his " Outlines of the Classification of 

 Plants," American edition, Chapter VII. 



slightly enlarged, r, brown sclerenchy- 

 ma, forming a hard (-heath beneath the 

 epidermis ; p, colorless parenchyma of 

 the fundamental system ; ig, inner fibro- 

 vascular bundles ; ag, the broad upper 

 band of the outer bundle /one ; pr, a 

 band of elongated thick-walled cells, 

 sclerenchyma or fibrous tissue a second 

 one occurs on the other side of the cen- 

 tral bundles. Ji, the separated upper 

 fibro-vascular bundle of the stem (rhi- 



