6 1 8 PHA NER OGA MS. 



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 Hilum 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 Corydalh), generally as a wart pitted in the middle. 

 When outgrowths occur on the seed, either along the raphe, as in Chelidonium majus, 

 Asarufn, Viola, &c., or as a cushion covering the micropyle as in Euphorbia, they are 

 variously called Ci^est, Strophiole, or Caruncle. The j4ril 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, Phoenix, Phyielephas, Crinum, &c. 

 In the Naiadese, Juncaginese, Alismaceae, 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 Helobise 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 Sci. 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 as 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.] 



