. Critical researches on the potamogetons. KUNGL. SV. VET. AKADEMIENS HANDLINGAK. BAND 55. N:0 5. 59 a more or less prominent boss. Endocarp thick-walled, epicarp thin, lid narrow, prominently keeled. Peduncle lacking the furrows has an oval crosscut form. Respecting the stem-anatomy P. cris-pus is perfectly lacking interlacunar and subepidermal strands but the epidermis, in compensation, is endowed with a one- celled pseudohypodermal stratum. Endodermis of 0-cells, vascular bundles of the stele arranged chiefly as in the following groups. The leaves are also lacking mechanical strands except
. Critical researches on the potamogetons. KUNGL. SV. VET. AKADEMIENS HANDLINGAK. BAND 55. N:0 5. 59 a more or less prominent boss. Endocarp thick-walled, epicarp thin, lid narrow, prominently keeled. Peduncle lacking the furrows has an oval crosscut form. Respecting the stem-anatomy P. cris-pus is perfectly lacking interlacunar and subepidermal strands but the epidermis, in compensation, is endowed with a one- celled pseudohypodermal stratum. Endodermis of 0-cells, vascular bundles of the stele arranged chiefly as in the following groups. The leaves are also lacking mechanical strands except in the margins, where a faint strand is present. Thus P. crispus is a genuine non-schlerenchymatous species. The epidermis-cells of the upper surface of the leaves are not so deep, radially seen, as those of P. Robbinsii and the same is the case with the next following groups. The rhizome has not the same cross-cut form as the stem, but a nearly cir- cular or faintly oblong one, which, besides, seems to beacharacteristic of the rhi- zomes of all species. The epidermis-cells are longer, about 4—10 times the width; in the stem, to mechanical purpose, only 2—4 times (fig. 22, C, D). The air chan- nels are reduced both in size and . 1 number. The bundles of the stele are separated, and beside this there are three lateral ones on each side. The endodermis-cells are weaker like all mechanical dispositions for the rest. But these arrangements return also regularly in the rhizomes in ge- neral. The compression of the leafy shoot in this and other species is therefore an evident arrangement for mechanical purposes by making all parts more flexible and pliant in the water. The enlarged, rounded borders of the stem and branches of this and other species, again, make the plant float more easily by their being pierced by larger air-filled channels. The fusion or reduction of the lateral bundles of the stele of the stem evidently depends on the necessity of making place in the strongly c
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Keywords: ., bookcentury1900, bookcollectionbiod, bookdecade1910, bookyear1916
