. Critical researches on the potamogetons. KUNGL. SV. VET. AKADBMIENS HANDLINQAR. BAND 55. N:0 5. 135 underneath, either totally disappear or become reduced to a minimum. Those bast- bundles are present in P. conjmigens m. in full and in a form of 2â5-celied strands, and in P. dimorpJius at intervals and consisting of only 2â4 cells each. P. diversifoUus and P. spirilliformis m. are destitute of them altogether. The endodermis of P. dimorphus and spirilliformis m. has thin-walled 0-cells, whereas the two other species have rather thick-walled endodermis-cells and, besides, a richer sclerenchym
. Critical researches on the potamogetons. KUNGL. SV. VET. AKADBMIENS HANDLINQAR. BAND 55. N:0 5. 135 underneath, either totally disappear or become reduced to a minimum. Those bast- bundles are present in P. conjmigens m. in full and in a form of 2â5-celied strands, and in P. dimorpJius at intervals and consisting of only 2â4 cells each. P. diversifoUus and P. spirilliformis m. are destitute of them altogether. The endodermis of P. dimorphus and spirilliformis m. has thin-walled 0-cells, whereas the two other species have rather thick-walled endodermis-cells and, besides, a richer sclerenchymatous tissue in the central cylinder. The interpretation of the singular development of the anatomic structure in the branches above the prim- ary spike lies in the fact that those branches partly must serve as peduncles, which in all these species are ex- tremely short. Consequently they need an internal struc- ture making them stiff like a peduncle and apt to bear up the spikes. This is obtained by a coarser central cy- linder with numerous free bundles and a pseudo-hypo- derma along the epidermis. P. spirilliformis m., always lacking the subepidermal strands as a compensation of them possesses very short epidermis-cells, 2â3 times as long as broad, while the other species have longer epi- dermis-cells: conjungens m. about 5 times the width, and dimorphus and diversifoUus respectively 5â10 and 10â20 times the width. The submersed leaves of all the species are rich in lacunae but poor in sclerenchymatous tissue. The ligules of P. Nuttallii very much resemble those of the first four species as to the membranous structure, the venation, and truncate apex, but are free from the leaves and open. The submersed leaves of the Euhyhridi m. are sheathing and endowed with a ligule. Sheaths and ligules typically connate, and like those of the Pusilli connati smooth and not plicate at the back as in some of the Coleogeions. After performed primary function the sheath longitudinally b
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Keywords: ., bookcentury1900, bookcollectionbiod, bookdecade1910, bookyear1916
