S YNOPSIS OF THE NA TURAL . ORDERS. xxiii 



SlJB-KlXGDOM II. Cryptogams, or Acotyledons, or Flowerless 



plants. Plants not provided with stamens and ovules as in Phsenogams. 

 Seeds represented by minute spores which contain no embryo. 



CLASS I. Aero gens. Plants with a distinct stem. 



SUB-CLASS Vasculares. Stem with vascular tissue. Spores con- 

 tained in a spore case (sporangium), and developing a prothallus in 

 germination. 



* Spores of one kind. 



90. FILICES. Sporangia usually very minute, situated on the margin or 

 under surface of the leaf (frond) } rarely larger, in separate spikes or 

 panicles. Fronds usually circinate in vernation, (p. 507.) 



91. EQUISETACE^E. Sporangia 2-valved, on the under side of peltate 

 scales that are arranged in terminal cones. Spores with 4 filiform clubbed 

 appendages rolled round them. Stems erect from a creeping rootstock, 

 cylindric, hollow, grooved, septate, simple or with whoiied branches and 

 with toothed sheaths at the joints, (p. 521.) 



92. LYCOPODIACE,E. Sporangia not very minute, situated in the axils 

 of the leaves, or of the scales of a cone. Fronds usually circinate in 

 vernation, (p. 523.) 



* Spores of two kinds. 



93. SELAGINELLACE^B. Sporangia not very minute, situated in the axils 

 of the scales of a cone or at the bases of subulate leaves. Spores of 2 

 kinds ; the larger developing a prothallus within its coat ; the smaller 

 containing antherozoids. Decumbent or prostrate plants with small 

 imbricating leaves of 2 forms ; or stemless water plants with subulate 

 leaves, (p. 525.) 



94. MARSILEACEJE. Sporangia (membranous sacs) very minute, enclosed 

 in the cells of a globose receptacle near the base of the frond. Spores of 

 2 kinds ; the larger developing a prothallus ; the smaller containing 

 antherozoids. Marsh or water plants, rarer on dry soils, (p. 526.) 



