498 INTRODUCTORY PLANT SCIENCE layer. In certain species, the capsule con til1Ues to grow as long as the gametophyte lives. The presence of a meristcm in A11tlioceros and an aerating system complete with sto mata may indicate that Antlwceros evolved from ancestors with even ·larger· and more 1. Civ complex sporophytes. These features may Bryophyt be vestiges from a more complex ancestral. 2. Wh sporophyte. that ti alga ? 3. De� ORIGIN AND RELATIONSHIPS OF THE Bryophyt, BRYOPHYTA 4._ characteri Little is known with certainty about the r are small origin and evolution of the bryophytes. The ' tall. ( B) fossil record is too fragmenta to enable • ry s true roots us to trace their evolutionary history. Frag ,, sperms ar mentary remnants of thallose liverworts, spore idium and mother\4'/ttN) which resemble present-day liverworts, have cell Jar arch� been foum! in rocks of Carboniferous age, bryophyt as have structures that may be remains of more com mosses. all bryoph The immediate ancestors of the bryo bryo whicl phytes were probably more complex plants from the have an i than present-day forms. In other words, the gametophy evolutionary tendency has been one of re- with a dip1 duction instead of increased complexity. •• • • • spores If evolution has progressed . from more • . . •, .... • s. __ complex sporophytes to those of simpler • . . vascular p Anthoceros . form, the sporophyte of wou1d • • green algat be considered more ancient than that of • (D) red Marchantia or Riccia. Because Riccia has Fig. 35-16. longitudinal section of the spo 6. How the most reduced sporophyte, it would be t·:i;,hyte of Anthoceros. phytes nev the most re.cent b ophyte. 7. __ ry with a (A) As evolution progressed, the gameto., 8. __ phytes a1so became reduce . · The ancestors rophyte was the most advanced b ophyte ry Riccia produced ii of the bryophytes had erect gametophytes ins:ead of the most primitive one. archegonia, and radially arranged leaves. From such witr, its simple sporophyte was considered . antheridia. ancestors the flat g�metophytes of liver most primitive. Furthermore, it was be 9. __ worts and homworts evolved. lieved that Anthoceros may have given rise of a bryopl The concept previously o;.:.tbed is the one to the vascular plants, a hypothesis not gen is called (, in vogue today and is just the opposite of erally accepted today. Here, as in other as gonium, (I the one which was fashionable a decade or pects of science, there are always at least 10. - two ago. The change in idea w11s not the two features in the development of a hy eggs by (A the wind, (C result of the discovery of new features but pothesis: ( 1) the collection of data, and ( 2) 11. -- 5imply n different way of reasoning from the interpretai:ion of the data. Vast amounts Ing E Eoot, the same facts. In earlier yeen it was be of data have accumulated ar.d wait the de a (A) zygol liev"d !hat Ai'l.thoceroa with [',s c��.iplex spo- velopment of new theories. r,hyte, (D) I