FILICES. (FERNS.) 589 



13. WOODSIA. Indusium very thin or obscure and evanescent, bursting into irreguLir lobe* 

 9r cleft into a fringe of hairs. 



TKIBK VII. ASPIDIE^E. 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. CYSTOPTERI3. 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. 

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

 the fruit-dots. 



SUBORDER II. O S M UN D I N E ^E . THE FLOWERING FERN FAMILY. 



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

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



TRIBE VIII. SCHIZE^E. Sporangia oblong or oval, sessile, with a circular striate-rayed 

 portion at the apex, opening down the outer side. 



16. SCH1ZJSA. Indusium none : sporangia covering one side of the linear pinnse of the naked 



and stalk-like fertile frond. 



17. LYGODIUM. 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. OSMUNDI3.9S* Sporangia globose, peuicelled, opening down the outer side 

 BO as to be two-valved. 



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



SUBORDER III. OPHIOGLOSSE^E. 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. BOTKYCIIIUM. Sporangia distinct, crowded in compound or pinnate spikes. Sterila 



frond divided. 



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



SUBORDER I. FOL.YPODINEJE. THE TRUE FERN FAMILY. 



1. POLYPODIUUI, L. POLYPODY. (Tab. 9.1 



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 vcinlct. - ' 

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

 (whence the name, from TroXu, many, and TTOUS, foot). 



4 1. POLYPODIUM PKOPER. Veins free (not connected by cross veinlets). 

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



