FILICES. (ferns.) 589 



12. WOODSIA. Iudusium ver}' thin or obscure and evanescent, bursting into irregular lobes 



or cleft into a fringe of hairs 



Tribe VII. ASPIDIEiE. Fructification dorsal: the fruit-dots borne on the back 

 (rarely on the apex) of a vein, orbicular or roundish, rarely oblong and then placed 

 across the vein, furnished each with a special indusium which covers the sporangia when 

 young, and is fixed by the centre or by one side, opening at the other side or all around 

 the margin. No general or accessory indusium formed of the margin of the frond. 



* Veins all free (none anastomosing) : fertile fronds not very different from the sterile 



13. CYSTOPTERIS. Indusium hood-like, broadly fixed by the inner side partly under the 



fruit-dot, free and early opening on the outer. 



14. ASPIDIUM. Indusium flat, orbicular or kidney-shaped, opening all round the margin. 



* * Veins of the sterile frond reticulated : fertile frond very unlike the sterile. 



15. ONOCLEA. Fertile frond contracted, the divisions rolled up into globular bodies enclosing 



the fruit-dots. 



Suborder II. O S M U N D I N E M . The Flo wering Fern Famll y. 



Sporangia variously collected (large), destitute of any proper ring, cel- 

 lular-reticulated, opening lengthwise by a regular slit. (Tab. 13.) 



Tbibe VIII. SCHIZEJE. Sporangia oblong or oval, sessile, with a circular striate-rayed 

 portion at the apex, opening down the outer side. 



16. SCHIZJ5A. Indusium none : sporangia covering one side of the linear pinnae of the naked 



and stalk-like fertile frond. 



17. LYG0DIU5I. Indusia in the form of scales imbricated in 2 ranks on one side of the fer- 



tile lobes of the leafy climbing frond. 



Tribe IX. OSMUNDEiE. Sporangia globose, peuicelled, opening down the outer side 



so as to be two-valved. 



18. OSMUNDA. Sporangia naked, covering contracted fronds or parts of the frond. 



Suborder III. OPHIOGLOSSE^. The Adder's-tongue Fam. 



Sporangia spiked, closely sessile, naked, coriaceous and opaque, not re- 

 ticulated or veiny, destitute of a ring, opening by a transverse slit into 2 

 valves, discharging very copious powdery spores. — Fronds straight, never 

 rolled up in the bud ! (Tab. 13.) 



19. BOTRYCIIIUM. Sporangia distinct, crowded in compound or pinnate spikes. Sterilo 



frond divided. 



20. OPHIOGLOSSDM. Sporangia cohering in a 2-ranked simple spike. Sterile frond entire. 



Suborder I. POLYPODiNE^. The TrUe Fern Family. 



1. POLYPODIUM, L. Polypody. (Tab. .9.) 



Fruit-dots round, naked, variously or irregularly scattered over the back of 

 the flat and expanded leaf-like frond, each borne on the end of a veinlet. — 

 Eootstocks creeping, often covered with wool-like chaff, and with tufted branches 

 (whence the name, from 7r6Xv, many, and ttovs, foot). 



$ 1. POLYPODIUM Proper. — Veins free (not connected by cross ueinlets). 



* Fronds simply and deeply pinnatifid, evergreen, glabrous : fruit-dots large. 



50 



