MONOCOTFLEDONS. 
619 
manniaceae, the parts of the embryo of the ripe seed are not differentiated; it 
consists of a round mass of tissue on which the plumule is developed only during 
germination. 
Germination^ either begins at once with the lengthening of the roots — their 
Fig. 419.— Germinatiun of Phoenix daclyli/ei-a : / transverse section 
of the doniiant seed; ///—/^^ different stajjes of germination [IV t\\Q 
natural size) ; A transverse section of the seed at xx in IV; B transverse 
section at x y, C bX. ä z ; e the horny endosperm, j- the sheath of the 
cotyledon, st its stalk, c its apex developed into an organ of absorption 
which gradually consumes the endosperm and at length occupies its 
place, lu the primary root, 7u' secondary roots, b' b" the leaves which 
succeed the cotyledon, b" becomes the first foliage-leaf: in B and C its 
folded lamina is seen cut across. 
FiCf. 420.— -Plant oi Polyi^ona/ui/i uutlfifloyion 
in its second year ; B its stem magnified, 7V the 
unbranched primary root, 7u' lateral roots spring- 
ing from the stem st, I foliage-leaf of the second 
year, k bud, c the scar where the cotyledon was 
attached, i and 2 scars of the first sheath-leaves 
which precede the foliage-leaf /. /, // the suc- 
ceeding sheath or cataphyllary leaves of the bud 
in B. {Cf. Fig. 143- ) 
protrusion causing in Grasses the rupture of the root-sheath which envelopes them, 
and which remains attached to the axis of the embryo as the coleorhiza (Fig. 123), 
— or, as is more commonly the case, the lower part of the cotyledon lengthens, 
See Sachs, Bot. Zeitg. 1862 and 1863. 
