. Heredity and evolution in plants . THE EVOLUTION OF PLANTS 2IQ sexual—in effect a microsporophyll or a megasporophyll,from which complex forms were derived by latter view, however, is not in harmony with avail-able evidence from fossil plants, such as that afforded byCycadeoidea. The strobiloid theory of the flower seems in the presentstate of our knowledge to stand alone as a working hy-. A B c v-v D FIG. 103.—Theoretical stages in the reduction (from Cycadeoidea tomodern Angiosperms) of staminate discs represented as segments. A,any common campanulate form with simple stam
. Heredity and evolution in plants . THE EVOLUTION OF PLANTS 2IQ sexual—in effect a microsporophyll or a megasporophyll,from which complex forms were derived by latter view, however, is not in harmony with avail-able evidence from fossil plants, such as that afforded byCycadeoidea. The strobiloid theory of the flower seems in the presentstate of our knowledge to stand alone as a working hy-. A B c v-v D FIG. 103.—Theoretical stages in the reduction (from Cycadeoidea tomodern Angiosperms) of staminate discs represented as segments. A,any common campanulate form with simple stamens (, morningglory); B, hypothetical Cycadeoid reduced to a single synangium to eachfrond component; C, inner view of a sector of a Williamsonia mexicanadisc; D, sector of a Cycadeoidea dacotensis disc with the pair of shoulderspurs borne by each frond. (After Wieland.) pothesis. If we reject it, we are left without any historicalclue to the origin of the floral structure of we accept it, the Primitive Angiosperm must be cred-ited with a flower resembling that of Magnolia or Lirio-dendron in general From this it follows that theMagnoliacecB, must be among the most primitive, if not themost primitive, of all Angiosperms, as Wieland first andHallier later and independently pointed out. 1 Sargant, Ethel. The reconstruction of a race of primitive Bot. 22:121-
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