XIV COMPENDIUM. 



SUBORDER II. < AE.A1I tltll\i:\i: (Heterospore Equi 

 setales). Contains extinct genera only, (') 



ORDER LYCOPODIALES. 



Differs from the Filicales in having the stems always solid, sometimes 

 articulated, generally more strongly developed than the leaves, with the 

 leaves erected in the bud. 



Leaves seriate, aggregate, or placed in spirals or whorls, the fertile 

 ones (sporophylla) forming close or lax terminal or lateral spikes, or 

 placed in alternate cycles with the barren ones so as to form a dense 

 rosette, with the sporangia placed singly in the axils. 



SIRORDER I. I,V< OIOIII\i:tB: (Isospore Lycopo 

 diales, Club mosses). Leaves without a ligula at the base. 

 Sporophylla forming spikes or arranged all down the stem. 

 Sporangia and spores isomorphous; spores producing independent 

 prothallia on which are developed antheridia and archegonia. 



FAMILY XIV. PSILOTACEAE. Leaves simple, either well-developed 

 and crowded along a subcylindrical stem, or rudimentary 

 and laxly 2 3-seriat along a flattened or angular, mostly 

 branched stem. Sporangia 2 3-locular, on 2-foliolate or 

 2-dentate sporophylla. 



GENUS 100. TMESIPTEBIS. Stems rather cylin- 

 drical. Sporophylla stalked, 2-foliolate. Sporangia 

 2-locular, smaller than the sporophylla. 



GENUS 101. PSILOTUM. Stems flattened or an- 

 gular. Sporophylla sessile, deeply 2-dentate. 

 Sporangia 3-Iocular, larger than the sporophylla. 



( J ) With 2 families; the Calamariaceae and the Protocalamariacear, 



the former the ancestral family of the Equlsetaceae. Poton., in Engl. & Prantl, 

 Nat Pfl.Fam., I 4 , 551 & 558. 



