494 



CRYPTOGAMOUS OR FLOWERLESS PLANTS. 



spirally rolled up or circinate in vernation (except in one subor- 

 der), usually rising from prostrate or subterranean rootstocks, 

 sometimes from an erect arborescent trunk (Fig. 94), and bearing, 

 on the veins of their lower surface, or along the margins, the sim- 

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

 or sporangia), opening in various ways, and discharging the nu- 

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

 a stipe. There are three principal suborders, viz. : 



1152 1153 IMS 



929. Sllbord, Polypodinese, Sporangia collected in dots, lines, or 

 variously shaped clusters (sori or fruit-dots) on the back or mar- 



FIG. 1147. Asplenium (Camptosorus) rhizophyllum (Walking Fern) ; the fronds rooting, as 

 they frequently do, at the apex; the sori occupying the reticulated veins on the back. 1143. 

 Division (pinnula) of a frond of Aspidium (Nephrodium) 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 margin. 1149. Magnified sporangium of this division of Ferns, with its stalk, 

 and elastric ring partly surrounding it; which, tending to straighten itself when dry, tears 

 open the sporangium, shedding the minute spores (1150). 1151. Schizaea pusilla of about the 

 natural size, with simple and slender radical leaves; the contracted fertile frond pinnate. 

 1152. A division (pinna) of the fertile frond, magnified, showing the sessile sporangia occupy- 

 ing its lower surface. 1153. One of the sporangia more magnified; they have no proper ring, 

 and open by a longitudinal cleft. 1154. Ophioglossum vulgatum (Adder- tongue) ; the sporan- 

 gia forming a two-ranked spike on a transformed and contracted frond : a, portion of the spike 

 enlarged, showing the coriaceous sporangia, destitute of a ring and opening transversely. 



