Sy stematic Botany : Bryophyta : Pteridophyta. I. 



LAND FLORA : as constituting the autotrophic vegetation of subaerial 

 environment (beyond the horizon of saprophytic phyla of Fungi), expresses the pro- 

 gression of plant-life from the medium of water to that of atmosphere ; involving not 

 only the factor of diminishing water-supply (ultimately reduced to a vanishing point), 

 but more definitely that of nutrition in terms of food-salts no longer available in 

 the general medium, and implying the mechanism of absorption, conduction, and 

 transpiration. 



Older phases of sexual reproduction, involving fertilization by mobile gametes 

 in a watery medium, are long retained ; but dispersal is provided for by the evolution 

 of wind-borne spores, in a manner paralleling that of many subaerial Fungi, as spores 

 produced in a sporangium. 



Three main lines of advance, roughly indicated as (i) Bryophyta (Mosses), 

 (2) Pteridophyta (Ferns), (3) Phanerogams (Seed Plants), not necessarily in linear 

 sequence, are to be regarded as parallel phases of progression, passing successively 

 to higher stages of land-organization. 



BRYOPHYTA, including Mosses (Bryineae), with Liverworts (Hepaticae) 

 and Jungermanniae : one general plan of organization and life-cycle common to all, 

 and the plant-types of no great size or importance : Sphagnum, the Bog-Moss, alone 

 attains special economic and geographical significance. 



The Life-cycle presents a definite alternation of generations, in which the sexual 

 phase is still dominant, as the individual receiving the name, and is attached to the 

 substratum by rhizoids, absorbing freely over its entire surface; hence requiring 

 a saturated atmosphere, or copious atmospheric precipitations. 



The sexual organs are antheridia (0*) and archegonia ($>) ; the flagellated 

 antherozoids are 2-ciliated ; the oosphere is solitary in the venter of the archegonium, 

 and is fertilized in situ. The zygote (oospore) develops directly to a parasitic sporo- 

 phytic phase, which remains permanently attached to the gametophyte, being wholly 

 dependent on it for water-supply, and reducing to a simple capsule-like body (sporo- 

 goniwn), more or less stalked, and devoted to the production of air-borne spores : the 

 latter are produced in great numbers, in tetrad-groups following a stage of meiosis. 



All the types are more or less decadent, and may be regarded as vestigial relics, 

 restricted to distinctly inferior biological stations ; e. g. mosses on walls or in shady 

 hedges, on peaty soil, among grass, on the bark of trees, especially in tropical rain- 

 forests : from the standpoint of higher vegetation an indication of inferior or ill-drained 

 soil. The more familiar and more striking types include : 



I. Polytrichum commune, a large tussock-form, the shoots of the gameto- 

 phyte growing in close association, a foot high or more, and bearing short acute 

 leaves in spiral sequence. The apex is controlled by a 3-sided apical cell, each seg- 

 ment from which produces a leaf: the leaf-laminae bear plates of protosynthetic 

 tissue on their upper surface, and the growing-point is enclosed in a bud-aggregate. 

 Archegonia and antheridia are produced in spring at the apices of special shoots, the 

 latter in lateral groups in leaf-axils. Fertilization effected in rain-water (May) ; the 

 embryo grows in the enlarged archegonial cavity, taking up a portion of it with 

 shaggy hair-growth as calyptra, and elongating to a stalk (seta), 2-3 in. long, and 

 a radially symmetrical capsule (7 mm.): the latter differentiates a wall, air-spaces, 

 archesporium, columella, &c. ; an apop/iysis-region with stomata, intercellular spaces, 

 cuticle, implies a transpiration-mechanism. The archesporium gives rise to spore- 

 tetrads, and finally spores, 10 ^ diam. ; the apex differentiates a conical operculum 

 which is shed to expose the peristotne-region of teeth and epiphragm, constituting 

 a sprinkling-mechanism for wind-dispersal of the spores. The latter germinate on 

 damp ground to give a filamentous Protonema-stzge, from which leafy shoots are 

 produced as buds, differentiating a 3-sided apical cell and parenchymatous organ- 

 ization. Note. The sporogonium is haustorial, and so initiates a transpiration current, 

 but there is no direct absorption from the soil solutions. 



II. Funaria hygrometrica, a small Moss-type, on walls or unoccupied burnt 

 ground, 1-2 in. high only : the gametophyte is a mere rosette of leaf-laminae, 1 cell 

 thick, with mid-rib ; apical growth by 3-sided cell. Antheridia and archegonia are 

 borne on separate plants, in terminal sori only ; archegonia 200 jx long, and oosphere 



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