CRYPTOGAMOUS OR FLOWERLESS PLANTS. 495 



gins of the frond or its divisions, stalked, cellular-reticulated, the 

 stalk running into a vertical incomplete ring, which by straighten- 

 ing at maturity ruptures the sporangium transversely on the inner 

 side, discharging the spores. Fruit-dots often covered, at least 

 when young, by a membrane called the involucre, or indusium. 



930. Subord, OsmimdinefB, Sporangia variously collected, desti- 

 tute of any proper ring, cellular-reticulated, opening lengthwise by 

 a regular slit. 



931. Subord, Opllioglosseae, Sporangia spiked, closely sessile, 

 naked, coriaceous and opaque, not reticulated, destitute of a ring, 

 opening by a transverse slit into two valves, discharging the very 

 copious spores which appear like floury dust. Fronds straight, 

 never rolled up (circinate) in the bud ! 



932. Ord, Lycopodiaceee (the Club-Moss Family). Plants with 

 creeping or erect leafy stems, mostly branching; the crowded 

 leaves lanceolate or subulate, one-nerved. Thecse sessile in the 

 axils of the leaves, sometimes all collected at the summit under- 

 leaves which are changed into bracts and crowded into a kind of 

 ament, one-celled, or rarely two- to three-celled, dehiscent, con- 

 taining either minute grains, appearing like fine powder, or a few 

 rather large sporules ; both kinds often found in the same plant. 



-Ex. Lycopodium (Club- Moss, Ground Pine, Fig. 89-93), Psi- 

 lotum. Appended to this family, rather than to the next, is the 



933. Subord, Isoetineee (the Quillwort Family), consisting of a 

 few acaulescent submersed aquatics, with sporangia in the axils 

 and immersed in the inflated base of the grassy stalk-like leaves. 

 Ex. Isoetes. 



934. Ord, Hydropterides, Aquatic cryptogamous plants of diverse 

 habit, with the fructification borne at the bases of the leaves, or on 

 submerged branches, consisting of two sorts of organs, of dubious 

 nature, contained in indehiscent or irregularly bursting involucres 

 (sporocarps) : comprising the 



935. Subord, Marsilese (the Pepperwort Family) ; with creeping 

 stems; the leaves long-stalked, circinate in vernation; of four 

 obcordate leaflets in Marsilea, or filiform and destitute of leaflets 

 in Pilularia (the Pill wort). 



936. Subord. Salvillieae ; which are free floating plants, with al- 

 ternate and sometimes imbricated sessile leaves ; the fructifica- 

 tion borne on the stem or branches underneath. Ex. Salvinia, 

 Azolla. 



