220 THE SCOTTISH BOTANICAL REVIEW 



Leaves retain their primitive character longer than stems which 

 carry all the organs. 



The stem is parvifoliate in Umbelliferse. the leaves grandifoliate. 

 If the monocotylous type be derived from dicotylar forms, the stem 

 would not remain the same and leaves become grandifoliate ; but if 

 dicotylous forms are derived from monocotylous, the stem might 

 become parvifoliate and the leaves remain grandifoliate and stem 

 become parvifoliate. Scattered bundles are found in the stem of 

 Umbelliferse, and it is not truly parvifoliate. 



In Ranunculaceae the flower is primitive and the habit grandi- 

 foliate. They have evidently not been derived from a woody 

 parvifoliate type; nor are Nymphjeacese — said to retain their grandi- 

 foliate habit owing to adaptation to an aquatic habit, for that induces 

 reduction and concentrated bundles, to form a compact mass in the 

 centre of the stem. Indeed, they retain their habit although aquatic. 

 Berberidaceae, Calycanthace^, Magnoliaceae possess primitive 

 flowers, sheathing leaf-bases, and retain something of the grandi- 

 foliate habit. The bundles are amphivasal where scattered — a 

 character common to both groups of Angiosperms. 



Miss Ethel Sargant holds the view that both monocotyledons and 

 dicotyledons are monophyletic. The absence of a cambium is said 

 to be due to reduction. The stem-structure of Liliacese is regarded 

 as primitive, e.g. in Ane/narrhena, with its bisymmetrical structure: 

 the last stage in the fusion of the cotyledons. Other groups of 

 LiliiflorcTC exhibit the same type. Comparison with pseudomono- 

 cotyledons and with Eranthis and Podophyllum, the latter arrested 

 on Its way to become a monocotyledon, confirms this. The correla- 

 tion of this feature with the geophilous habit suggests that it is the 

 cause of the fusion of the two cotyledons to form one, which is 

 regarded as a necessary economy by reduction (;f material expended 

 in assimilating tissue, owing to the short growing season of such 

 plants as Alpine, bulbous, and tuberous plants. In such plants the 

 leaves are crowded, giving rise to concentric or scattered bundles. 

 Linear leaves assist in elongation. Short-lived roots characterise 

 lowland plants habituated to a short growing season. Albuminous 

 seeds are found in dicotyledonous geophytes. Thus Miss Sargant 

 holds the view that the monocotylous furms are reduced owing to a 

 geophytic habit. 



Darwin, in his "Movements of Plants," ^ says: "We may infer 

 that there is some close connection between the reduced size of one 

 or both cotyledons and the formation, by the enlargement of the 

 hypocotyl or of the radicle, of a so-called bulb." 



Pseudomonocotyledons are geophytes as well as many mono- 

 cotyledons, and thus the common habit is taken to be the cause 

 of the single cotyledon. 



As to the possession of a cambium, Queva has found this in second- 

 year tubers of Gloriosa superba, from which he regards dicotyledons 



1 1880, p. 97. 



