Lectures on the physiology of plants . phytes, with the Cryptogamsor Sporophytes. Nevertheless the fertilising apparatus of most Monocotyledons and Dicotyledonsappears to be strikingly different externally from that of the Gymnosperms. Whatis commonly termed a flower is simply the fertilising apparatus of these plants(which may therefore be contrasted as Flowering-plants in the narrower sense ofthe word with the Gymnosperms), but here again it is of course to be borne inmind that all such distinctions are only admissible when the typical forms in bothcases are contrasted with one another. It n
Lectures on the physiology of plants . phytes, with the Cryptogamsor Sporophytes. Nevertheless the fertilising apparatus of most Monocotyledons and Dicotyledonsappears to be strikingly different externally from that of the Gymnosperms. Whatis commonly termed a flower is simply the fertilising apparatus of these plants(which may therefore be contrasted as Flowering-plants in the narrower sense ofthe word with the Gymnosperms), but here again it is of course to be borne inmind that all such distinctions are only admissible when the typical forms in bothcases are contrasted with one another. It needs only a somewhat broader con-ception of the idea Flower to justify the application of the term even to a Fir-coneor even to the very unobvious fertilising apparatus of the Yew. Of course thedistinction between the flower of a Lily or of a Rose, and that of a Fir or Pineor other Gymnosperm is very great, but between the two, even externally considered,there are numerous stages of flower-development which show us that the difference. FIG. 439.—^ a pollen-grain (microspore) ofCeratozamia loiigi/olia, a Cycad. B emergenceof the pollen-tube ps from the ruptured outermembrane (exline) of the pollen-grain. At j/ areseen the sterile cells (Juranyi). FLOWERING-PLANTS. 757 is not one of principle but only of degree. That which conspicuously distinguishesparticularly the large and elegant flowers of true flowering-plants from those of theGymnosperms is the floral envelope, which is very often a double one and is thentermed Calyx and Corolla. Even the most magnificent flowers when stripped of theseenvelopes so that only the essential organs of reproduction remain, show nothingmore of the immense contrast indicated above, and we have here to do particularlywith these proper reproductive organs only, although I shall show in the next lecturethat the floral envelopes are by no means superfluous for starting the process offertilisation (i. e. pollination), and in many cases are in fact i
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectplantph, bookyear1887
