io fj. diam. ; antherozoid with 2 equal flagella. Fertilization in casual drops of water 

 at any season (ephemeral). Sporophyte as a pear-shaped capsule (3-4 mm.) on 

 a slender seta presenting hygrometric curvatures, with a membranous calyptra ; the 

 apophysis differentiates stomatal mechanism, the capsule a wall, air-space, and arche- 

 sporium, the latter giving rise to spores, matured at 20 p diam. The Peristome is 

 complex of 16 + 16 'teeth', exposed by the abscission of the operculum (1 mm.) to 

 constitute a grille for gradual wind-dispersal. The Protonemal juvenile stage may 

 multiply by gemmae. 



Marchantia polymorpha : a typical Liverwort on damp light soil in spring. 

 Gametophyte a dorsiventral dichotomously lobed thallus with apical cell (2 sided), 

 rhizoids on lower surface and areolate chambers on upper. Vegetative propagation 

 by gemmae produced in ' cups '. Antheridia and archegonia borne on special erected 

 shoot-systems, dioecious ; fertilization in casual water. The zygote gives a small 

 capsule (1 mm.); many such being formed on the under surface of the umbrella-like 

 female ' receptacle '. Sporophyte of short stalk (2 mm.) and capsule of wall and 

 spore-mass with elaters, dehiscing irregularly at apex. Protonema stage ill-defined. 



Cf. also Lunularia, Fegatella (Hepaticae), Pellia, Frullania (Jungermar.niae). 



PTERIDOPHYTA : including the great Fern-series (Filicineae), Horse-tails 

 (Equisetineae) and Club-mosses (Lycopodineae with Selaginella), a group of very 

 distinct phyla now left at a common horizon, in which 



The gametophyte is reduced to a vestigial leafless prothallus, in the general 

 case still green and autotrophic, bearing few antheridia and archegonia, the former 

 producing flagellated antherozoids (multiciliate in Ferns and Equiseta, biciliate in 

 Lycopods and Selaginelld). Fertilization of the oosphere of archegonium in casual 

 water-supply of rain or dew ; the plant vegetating only in a saturated atmosphere, 

 normally short-lived, but sexually efficient. 



On the other hand, the sporophyte acquires great size and differentiation as 

 a land-plant, receiving the recognized name, and becoming an independent organism 

 by the elaboration of roots absorbing directly from the soil ; in correlation with this 

 the transpiration-current is more effective, and vascular tissues (xylem with tracheides) 

 are initiated as special conduction-mechanism for a transpiration-current. The stem 

 is erect, radially symmetrical with leaves in phyllotaxis (spiral or whorled), and apical 

 growth is controlled by a 3-sided apical cell, or massive meristem (Lycopods). 



Asexual sporangia are borne on special leaves (sporophylls), and produce 

 spores, again formed in meiotic tetrads, to be discharged by the dehiscence of the 

 sporangia in air, wind-borne, 30 ^ diam. or so, and directly comparable with the 

 pollen-grains of Angiosperms. 



The sporophyte bearing foliage-leaves thus attains the general characteristics of 

 a ' land-plant ', while the sexual phase is vestigial, still essentially alga-like and aquatic. 



The existing main phyla are distinguished by special departures as the lineal 

 descendants of similar organism traced back to the Carboniferous Epoch, and beyond, 

 as plants of even arboreal habit, growing in forest-association, and consticuting the 

 bulk of the coal-beds (Calamodendron, Lepidodendron, Sigillaria). At the present 

 time the types are restricted to inferior biological stations (shade-plants, xerophytes, 

 aquatics) ; cf. : Filicineae of damp woodland and shaded base of warm forest-association. 



Equisetineae of swamps, Lycopods of hill-pastures, and as tropical epiphytes, 

 Selaginella as forest undergrowth. 



Filicineae are usually distinguished by large compound leaves, up to 30 ft. in 

 Tree-ferns, to the D.V. subterranean rhizome of Pteris (Bracken), sending up 1 com- 

 pound leaf each season. Sporangia normally on under-surface of the leaves ; special 

 types characteristic of main groups. Heterospory obtains in small reduced aquatic 

 forms as Salvinia, Azolla, Pilularia. 



Equisetineae, with no leaves beyond rudiments as ' teeth ', whorled branch- 

 systems with marked nodes and internodes ; terminal strobili of special sporophylls, 

 often on special shoots in spring, finest in E. Telmateia. 



Lycopods, axes dichotomously branched, leaves small and scale-like, xerophytic 

 habit ; sporophylls in spicate strobili, one sporangium per sporophyll, on the upper 

 surface only. Selaginella essentially similar, but typically D. V. shoot-systems, with 

 radial strobili bearing sporangia and spores differentiated as micro- and w^a-forms, 

 often in the same strobilus ; the megasporangium reduced to one tetrad of 4 large spores. 



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