Title
Page 09 – Transverse sections of the stem of an 8-months-old seedling
Creator
Date
c. 1940
Format
Description
Fig. j, cut at level of root initiation. Section shows approximate cross section of root, r (see Fig. for details of this stage of root initiation). Section cut at level 120 /ᵘ below preceding section.
Figs. k, cut at level 135 /ᵘ below section 10,
l, cut at level 60 /ᵘ below section 11,
m, cut at level 30 /ᵘ below section 12,
n, cut at level 30 /ᵘ below section 13,
o, cut at level 30 /ᵘ below section 14,
p, cut at level 60 /ᵘ below section 15,
q, cut at level 45 /ᵘ below section 16,
r, cut at level 45 /ᵘ below section 17,
s, cut at level 75 /ᵘ below section 18,
t, cut at level 60 /ᵘ below section 19,
u, cut at level 45 /ᵘ below section 20,
v, cut at level 120 /ᵘ below section 21,
w, cut at level 75 /ᵘ below section 22, and
x, cut at level 75 /ᵘ below section 23,
to show older stages of roots, r₁, r₂, r₃, r₄, r₅ and r₆ in lower portions of the stem. r, in Fig. 11, shows apex of this root and r₂, in Fig. 24, shows cross section near apex of this root. Because roots turn obliquely downward, rather than abruptly, in their course from point of origin, sections made through latter show base of root cut either longitudinally or obliquely, and rest of root in cross section. in w, notice: c, stem cortex; rc, inner root cortex; src, sclerosed outer root cortex; s, stem stele; rs, root stele; se, "stem endodermis" (see text); re, root endodermis; p, root pith. Notice vascular network, vn, at boundary between cortex and stele (see text) in sections of lower portions of stem; this is basipetal continuation of "ring" of specialized meristematic tissue shown in sections in higher portions of stem. Also notice b, leaf traces passing out from stelar region of stem, through leaf gaps, lg, left in vascular network.
Figs. k, cut at level 135 /ᵘ below section 10,
l, cut at level 60 /ᵘ below section 11,
m, cut at level 30 /ᵘ below section 12,
n, cut at level 30 /ᵘ below section 13,
o, cut at level 30 /ᵘ below section 14,
p, cut at level 60 /ᵘ below section 15,
q, cut at level 45 /ᵘ below section 16,
r, cut at level 45 /ᵘ below section 17,
s, cut at level 75 /ᵘ below section 18,
t, cut at level 60 /ᵘ below section 19,
u, cut at level 45 /ᵘ below section 20,
v, cut at level 120 /ᵘ below section 21,
w, cut at level 75 /ᵘ below section 22, and
x, cut at level 75 /ᵘ below section 23,
to show older stages of roots, r₁, r₂, r₃, r₄, r₅ and r₆ in lower portions of the stem. r, in Fig. 11, shows apex of this root and r₂, in Fig. 24, shows cross section near apex of this root. Because roots turn obliquely downward, rather than abruptly, in their course from point of origin, sections made through latter show base of root cut either longitudinally or obliquely, and rest of root in cross section. in w, notice: c, stem cortex; rc, inner root cortex; src, sclerosed outer root cortex; s, stem stele; rs, root stele; se, "stem endodermis" (see text); re, root endodermis; p, root pith. Notice vascular network, vn, at boundary between cortex and stele (see text) in sections of lower portions of stem; this is basipetal continuation of "ring" of specialized meristematic tissue shown in sections in higher portions of stem. Also notice b, leaf traces passing out from stelar region of stem, through leaf gaps, lg, left in vascular network.