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 .