* 

 SYNOPTICAL KEY TO THE ORDERS. xv 



SERIES II. CRYPTOGAMOUS OR FLOWERLESS PLANTS. Flowers without 

 stamens or pistils, in fruit producing spores instead of seeds. 



CLASS III. ACROGENOUS PLANTS. Growing from the apex of a distinct axis, 



mostly with distinct leaves. 



SUBCLASS I. VASCULAR ACROGENS. Plants with both woody and cellular tissue: 

 reproductive organs of one or both sexes produced upon a prothallus developed from 

 the spore. 



DIVISION I. ISOSPOROUS VASCULAR ENDOGENS. Spores only of one kind, the pro- 

 thallus bearing organs of both sexes. 



120. Equisetaceae, p. 329. Cylindric jointed hollow-stemmed plants, with toothed sheaths. 



Fructification in a terminal spike. 



121. Ophioglossaceae, p. 331. Fronds often fern-like, erect in vernation. Sporangia globose, 



coriaceous, in special spikes or panicles. 



122. Filices, p. 332. Ferns, with fronds circinate in vernation, bearing the fructification on the 



under surface or beneath the margin. 



DIVISION II. HETEROSPOROUS VASCULAR ACROGENS. Spores of two kinds, one pro- 

 ducing a prothallus with archegonia, the other smaller and containing antherizoids. 



123. Selaginelleee, p. 349. The two kinds of spores borne separately upon the upper side of the 



base of linear grass-like radical leaves or in the axils of small leaves arranged in 4 ranks 

 upon a stem. 



124. Marsiliaceae, p. 351. Spores of both kinds together in peduncled capsules borne upon a 



rhizome. Leaves filiform or pedately qiiadrifoliolate. In mud. 



125. Salviniaceee, p. 352. Small floating plants, the spores borne in separate capsules at the 



base of the frond. 



SUBCLASS II. CELLULAR ACROGENS. Plants with cellular tissue only" : reproduc- 

 tive organs borne upon the stem or branches. 

 A. Capsules mostly opening by a lid, containing numerous spores without spiral fibres (elatcrs). 



126. Musci, p. 353. Branches not regularly fascicled along the stem. Tissue of the leaves 



homogeneous. Spores of one kind. 



127. Sphagnaceee, p. 421. Branches regularly fascicled. Tissue formed of colorless cells and 



intermediate green linear ducts. Spores of two kinds. Pale flaccid bog plants. 



B. Capsule not opening by a lid : spores mixed with elaters. 



128. Hepaticae. Stems procumbent, leafy with alternate or distichous leaves, or thalloid. 

 C. Sporangium consisting of a single large spore surrounded by spirally arranged tubes. 



129. Characeae. Submerged aquatics, with whorled branches, consisting of tubular cells 



placed end to end. 



CLASS IV. THALLOGENS. Growth chiefly peripherical and horizontal, without 

 definite axis, mostly without leaves, and composed wholly of cellular tissue : spores 

 not developing a prothallus. [Added here to complete the Series.] 



130. Lichenes. Not parasitic, on exposed surfaces, prostrate and crustaceous or frondose, or 



erect, containing chlorophyllose granules. Reproductive organs of two kinds, apothccia 

 and sjyermogonia. 



131. Fungi. Parasitic, wholly without chlorophyll, the organs of vegetation (mycelium) mostly 



subterranean or concealed, the reproductive very various in form and structure. 



132. Algae. Aquatic, mostly submerged, not parasitic, always containing chlorophyll and 



usually highly colored. Reproductive organs very various. 



