6i8 
PHANEROGAMS. 
pericarp and the testa is to furnish means for the dissemination of the seeds in various 
ways ; structures which are morphologically very different thus attaining the same 
physiological development, while those which are morphologically similar attain the 
most various physiological development. A detailed enumeration is therefore more in 
the province of physiology and biology than in that of morphology and classification. 
(See Book III.) 
To complete the subject of nomenclature, it only remains to remark that the part 
of the seed where it has become detached from the funiculus — usually easily distin- 
guished after falling out — is termed the HHum or umbilicus. The micropyle is often 
also to be recognised, lying, in anatropous and campylotropous seeds, close beside the 
hilum (as in Faba, Phaseolus, and Corydalis), generally as a wart pitted in the middle. 
When outgrowths occur on the^seed, either along the raphe, as in Chelidonium majus, 
Asarum, Viola, Sec, or as a cushion covering the micropyle as in Euphorbia, they are 
variously called Crest, Strophiole, or Caruncle, The Aril which envelopes the base of the 
ripe seed or the entire seed as a fleshy succulent mantle and is easily removed from the 
true firm testa has already been described in detail. 
CLASS XI. 
MONOCOTYLEDONS. 
The Seed of Monocotyledons usually contains a strongly developed endosperm 
and a comparatively small embryo ; and this is exhibited in an especially striking 
manner in large seeds, such as those of Cocos, Phcenix,. Phytelephas, Crinum, &c. 
In the Naiadese, Juncagineae, Alismacese, and Orchideae, the endosperm is wanting 
from the first; and in the Scitaminese, where it is usually wanting, it is replaced by a 
copious perisperm. 
The Embryo is usually cylindrical, fusiform, and sometimes considerably 
elongated, and is then also curved spirally {e.g. in Potamogeton and Zanichellia) \ 
its form is not unfrequently that of an erect or inverted cone, in consequence of 
a considerable thickening of the upper end of the cotyledon. The axis of the 
embryo is generally very short and small in comparison to the cotyledon ; in 
the Helobiae on the contrary the axial portion of the embryo forms the greater 
part of it. At the posterior end of the axis is the rudiment of the primary root, 
in addition to which two or more lateral roots also originate in Grasses, which, like 
the primary one, are surrounded by a root-sheath (Fig. 124, see also p. 588). The 
embryo of Grasses is also distinguished by the presence of the Scutellum, an 
outgrowth of the axis beneath the cotyledon, which envelopes the whole of the 
embryo like a mantle, and forms a thick peltate plate on the posterior side where 
it is in contact with the endosperm ^ In the Orchideae, Apostasiaceae, and Bur- 
^ [Van Tieghem (Ann. des Sei, Nat. 5th series, vol. XV, 1872) gives a useful summary of the 
various views which have been held with respect to the homology of the parts of the embryo of 
Grasses, He regards the scutellum as the cotyledon, and what Sachs considers the cotyledon äs only 
its strongly developed ligule. According to Hegelmaier (Bot. Zeitg. 1874) the cotyledon of Grasses 
consists of two parts ; the one forms the scutellum, the other forms a sheath round the plumule.] 
