Text-book of botany, morphological and physiological . when ripe by its redor yellow colour and its sweet pulpy tissue. Here also the apical point lies in themiddle of the bottom of the hollow, and the inner surface of the wall of the urn isa portion of the outer side of the floral axis which has been turned in. To thiscorresponds the acropetal succession of the leaves (which, however, is only adhered toin a general way). It is clear that if the apical point lies at y (in //), the successionof leaves (in this case stamens st and carpels k) from above downwards must be termedacropetal. If an ad
Text-book of botany, morphological and physiological . when ripe by its redor yellow colour and its sweet pulpy tissue. Here also the apical point lies in themiddle of the bottom of the hollow, and the inner surface of the wall of the urn isa portion of the outer side of the floral axis which has been turned in. To thiscorresponds the acropetal succession of the leaves (which, however, is only adhered toin a general way). It is clear that if the apical point lies at y (in //), the successionof leaves (in this case stamens st and carpels k) from above downwards must be termedacropetal. If an additional proof of what has just been said were wanted, it would be fur-nished by the history of development of the flowers of Geum, a genus very nearlyrelated to the rose (Fig. 153). That part of the floral axis which bears the sepals /,the corolla c, and the stamens a a, is elevated in the form of a circular wall y y; butthe apical region which in Rosa entirely ceases to elongate, becomes again elevated CHARACTERISTIC FORMS OF LEAVES AND SNOOTS. 201. Fig. 153.—Longitudinal section of ayoung flower of Geum riiiale. as a conical body jf, bearing at its summit the apical point of the floral axis. Theorder of succession of the leaf-structures is again acropetal, and in consequence thestamens a are formed on the inner side of the axis y yfrom above downwards, the carpels which succeed themon .V from below upwards. In Geum and other Dryadeaethe urn y y spreads out at the time of fertilisation, itsmargin grows so vigorously in size that it expands in theform of a flat plate, and after the expansion its inner sur-face becomes the outer surface, in the middle of whichthe gynophore .v rises like a cone, and in Fragaria after-wards swells out greatly, becomes fleshy, and forms thestrawberry (a pseudocarp like the hip). It will be seen that the formation of the fig„the hip, andthe subsequently flat receptacle of Geum depends on adisplacement which is caused by vigorous growth of masse
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectbotany, bookyear1875
