









. 











240 DE. M. T. MASTERS ON THE MORPHOLOGY, 



This position of the stomates on the upper or lateral surfaces 

 of the cotyledons has heen specially observed by the writer in 

 PseudotsugaDouglasii^ Abies grandis, balsamea, cephalonica, 

 Apollinis,sachalinensis, sibirica ,Veitchii , Cedrtis atlantica, Libani, 

 Oryptomeria Lobbi, Cupressus Lawsoniana, sempervirens,funebris, 

 Pinus Jeffreyi, Retinospora pisifera, and Thuya gigantea. Engel- 

 mann * notes that in Sciadopitys the stomates are placed on the 

 lower surface of the cotyledons exclusively. 



Plumule. — The term plumule is not very accurately defined. 

 For our present purpose we may take it to be that portion of the 

 axis with its attendant leaves which is formed in the embryo 

 plant prior to germination above the cotyledons. Sometimes it 

 remains in the same condition as when first formed ; but gene- 

 rally it undergoes changes in size, Ac., during and after germi- 

 nation. The leaves which it produces are often different from 

 those formed on the other parts of the stem. Growth in the 

 plumule is for a time continuous, or at least relatively so ; so that 

 sometimes no definite limit can be observed between it and the 

 succeeding portion of the axis. At other times plumular growth 

 is arrested by the formation of a terminal bud invested by perular 

 scales, as I have observed in Pinus silvestr is, Pseudotsuga Dou- 

 glasii, Abies pectinata, sibirica, cephalonica, Piceaj>rientalis, and 

 P.Menziesii. How far this is a congenital character, or to what 

 extent it is due to external conditions, is uncertain. In Qingko 

 biloba there is a gradual transition between the perulse and 

 petiolar expansions to perfect leaves. Sometimes the axis above 

 the cotyledons lengthens before it produces any leaves, and then, 

 of course, the plumular or primordial leaves are removed from 

 the cotyledons by internodes. In other cases, as in Ceplialotaocus 

 Fortunei, Retinospora Jpisif era, R. obtusa, Thuya gigantea, Cu- 

 pressus sempervirens, C. Lawsoniana, C.funebris, and C. macro- 

 carpa, the first two leaves are close to the cotyledons and decus- 

 sate with them, while the subsequent pairs of leaves may be 

 separated by internodes. In other cases, again, the primordial 

 leaves are so crowded that they may be called tufted, as has been 

 observed by the writer in Frenela, Larix, various species of 

 Pinus, Retinospora obtusa, Picea orient alis, Thuya ^gigantea, 

 Pseudotsuga Douglasii, Abies cephalonica, grandis, sibirica, and 



'""inis species in which, as before stated, a true scaly winter- 



^ 







- 



> # * 



' 



1 Bevision of the Genus Pinus,' p. 3. 











* 

































■ 







, 



. 





















, 







- 





i 













