. Critical researches on the potamogetons. 16 J. O. HAGSTROM, CRITICAL RESEARCHES ON THE POTAMOGETONS. central cylinder of the peduncle exhibits the same structure as the upper portion of the stem, but the lateral bundles are often still more reduced or have disappeared. The anatomy of the leaf (fig. 4, D) exhibits a median vascular bundle surrounded by small air-channels, on either side of which one always meets with a row of wider lacunae and subepidermally a faint bundle in the very margin, the leaves accordingly being three-nerved, although to the naked eye only one-nerved. The so-called c
. Critical researches on the potamogetons. 16 J. O. HAGSTROM, CRITICAL RESEARCHES ON THE POTAMOGETONS. central cylinder of the peduncle exhibits the same structure as the upper portion of the stem, but the lateral bundles are often still more reduced or have disappeared. The anatomy of the leaf (fig. 4, D) exhibits a median vascular bundle surrounded by small air-channels, on either side of which one always meets with a row of wider lacunae and subepidermally a faint bundle in the very margin, the leaves accordingly being three-nerved, although to the naked eye only one-nerved. The so-called cross- veins are the extremely thin cross-walls of the lacunae. The species varies rather much, though considerably less than P. pectinaius. The upper part of the style (not the stigma) grows often in this species and in P. strictus somewhat protracted backwards forming a little beak. The fruit of the usual Baltic form as well as of most B end C ,P. forms both from brackish and fresh water is small, but there also occur large-fruited forms F especially on calcareous mud end iformce megacavpce, P. pycnoste- gus KiHLM.), in which the walls of the very stone grow thicker than they usually do. But the shape of the lid and the ven- tral part is unaltered. The lid is always rounded on the back, of about the same form drawn Fig. i. P. filifonnis Pers., A, Transverse section of stem, upper part, show- in. the fig. 116, H, The leaf- ing two barkbundles (sir), central stele outlined, \''. B, Transverse section -Jj-V, • T "U 1 f A ot central cylinder, more enlarged (oatlined) exhibiting two median bundles and WlCltll VarieS Slightly irom 0,5—1 two lateral ones, a, b-b corresponding to a, b-b in the cross-section of the leaf i ,i oVi^c + Via Unlrl nf^m (below) and of the sheath (fig. 3, B). C, Transverse section of the peduncle '""^ "*"^ •'^^'^ bllBdlllb IIUIU COm- with four bundles (outlined). D, Transverse section of a stem-leaf middle part, mOUlv 5 15 mill
Size: 1778px × 1405px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookcollectionbiod, bookdecade1910, bookyear1916
