500 



ILLUSTRATIONS OF THE NATURAL ORDERS. 



962. Ord. Filices {Fems). Leafy plants ; with the leaves {fronds) 

 spirally rolled up or cireinate in vernation (except in one suborder), 

 usually rising from prostrate or subterranean rootstocks, or in tree- 

 Ferns from an erect arborescent trunk (Fig. 100), and bearing on 

 the veins of their lower surface, or along the margins, the simple 

 fructification, which consists of one-celled spore-cases (thecce or spo- 

 rangia), opening in various ways, and discharging the numerous 



1298 



1293 



1288 



1291 



1287 1294 



minute spores. The stalk or petiole of the frond is termed a stipe. 

 — There ai'e four principal suborders, viz. : — 



FIQ. 1287. Camptosorus rhizophyllus (Walking Fern) ; the fronds rooting, as tliey fre- 

 quently do, at the apex ; the sori occupying the reticulated veins on the back. 1288. Division 

 (pinnula) of a frond of Aspidium Goldianum ; the roundish sori attached to the simple veins, 

 and covered with an indusium, which is fastened in the centre, and opens all around the mar- 

 gin. 1289. Magnified sporangium of this division of Ferns, with its stalk, and ela-stic ring 

 partly surrounding it ; which, tending to straighten itself when dry, tears open the sporangium, 

 shedding the minute spores (1290). 1291. Schiza^a pusilla of about the natural size, with simple 

 and slender radical leaves ; the contracted fertile frond pinnate. 1292. A division (pinna) of 

 the fertile frond, magnified, showing the sessile sporangia occupying its lower surface. 1293. 

 One of the sporangia more magnified ; they have no proper ring, and open by a longitudinal 

 cleft. 1294. Ophioglossum vulgatum (Adder's-tongue) ; the sporangia forming a two-ranked 

 spike on a transformed and contracted frond : a, portion of the spike enlarged, showing the co- 

 mceons sporangia, destitute of a ring, and opening transversely. 



