THE ANGIOSPERMAK 1585 



In many seedlings the first epicotyledonary leaves show at once the 

 character of the mature foliage. Examples are: Paeonta, Hepatica, Hedera, 

 Ampelopsis, and Salix. In many others there is a gradual transition from 

 simpler forms towards the mature form, as may also be seen in some buds 

 of trees. This is especially the case where the mature leaves are compound, 

 as in Robinia and Glxcine and in many other cases, especially in Rosaceae, 

 e.g., Rosa, Fragaria and Potentilla, the last named often showing a parti- 

 cularlv striking series of stages. The stool-shoots which arise from the 

 base of the trunk or the roots of many trees show a similar series of stages 

 in leaf development. In many Pyrolaceae, Lauraceae and Annonaceae the 

 first few leaves are much reduced and scale-like and the mature leaf form 

 appears suddenly at the fifth or sixth node. In Monocotyledons there may 

 be a similar gradual appearance of full leaf development, the first leaves 

 often having a well-formed sheath, but little or no leaf blade. The differ- 

 ences are, however, not so marked as in Dicotyledons. The question arises 

 whether this is a true recapitulation of an evolutionary series or not. The 

 probabilities are against it and it seems more likely that it is due to an 

 upward extension of the growth restriction which is evident in the coty- 

 ledons. 



We may now consider shortly how we may arrange the various seedling 

 conditions we have referred to, in a tabular order, as a classification of types 

 of germination. 



Dicotyledons 



Epigeal: Endospermic: Polygonaceae, Plantaginaceae, Ricimis (Fig. 

 1444) and many others. 

 Non-endospermic: Cruciferae, Lamiaceae, etc., Phaseolus 

 vulgaris (Fig. 1445). 



Hypogeal: Endospermic: Annonaceae, Hevea. 



Non-endospermic: Fagaceae, etc., Phaseolus multiflorus, 

 (Fig. 1446), Tropaeoliim. 



Monocotyledons 



Epigeal: Endospermic: Liliaceae, Butomaceae. 



Non-endospermic: Alismaceae. 

 Hypogeal: Endospermic: Palmae, Gramineae (Fig. 1447). 



Non-endospermic: Aponogeton only. 

 The case of Aponogeton deserves notice for its singularity. The coty- 

 ledon is a fleshy cone filling the seed. The latter floats and the embryo 

 drops out of it and germinates on the mud below water (Fig. 1448). 



The question of the evolutionary origin of the Monocotyledons has 

 often been debated on the ground of seedling structure. Since John Ray 

 first distinguished the two classes of Angiosperms on the number of their 

 cotvledons, this difference has tended to assume too great an importance 

 in theoretical arguments, since it is only one among several important 

 structural distinctions. 



