1909J Seedlings of Ph^nogamous Plants. 239 



primary root begins; but also here the hypocotyl and primary 

 root are of short duration as in Ranunculus . Dioncea muscipula 

 EUis (Fig. 22) belongs to the same type, and differs from most 

 of the other Droseraceae by the presence of a distinct primary 

 root, which aborts in most of these. It is interesting to notice 

 that the first leaf succeeding the cotyledons already shows the 

 peculiar structure so very characteristic of Sarracenia and 

 Dioncea. 



In these types, mentioned above, I have shown some of the 

 most striking modifications observable in the hypocotyl and the 

 primary root, while the cotyledons themselves merely differ in 

 respect to their shape. In the subsequent types, on the other 

 hand, we shall see that some modification may, also, be noticed 

 in these. Let us begin with Deniaria laciniata Muehl. (Fig. 30). 

 Of the two cotyledons only one becomes raised above ground 

 by means of its long petiole, while the other one is short-petioled 

 with the blade enclosed by the seed*; the blade of the green 

 cotyledon is obovate, large in proportion to the size of the 

 seedling. We notice, furthermore, the short, slender primary 

 root, which persists only through the first season. The hypocotyl 

 is very short, and the plumule soon develops into a small, 

 conical tuber, of which the first leaf generally pushes out during 

 the first season as a long-petioled leaf with a green, mostly 

 bicleft blade. In regard to the secondary roots, these show a 

 very rare position since they break out from the axils of the 

 cotyledons, one from each. In this way Dentaria laciniata 

 represents a very interesting type of seedling, dicotyledonous, it is 

 true, but with the normal development of only one of these; 

 The European species of Dentaria are, also, interesting, since 

 both cotyledons are hvpogeic in D. pinnata Lam., but epigeic in 

 D. bulhifera L., and D. digitata Lam. From this we learn that 

 the structure of cotyledons may be very distinct even among 

 closely related species. 



A still more remarkable type is exhibited by Podophyllum 

 peltatum L. (Fig. 31) in which the long petioles of the two 

 cotyledons form a tube at the base of which the plumule is 

 located; the primary root is well developed, and persists for 

 several years. During the first season the seed-leaves are the 

 only ones of the plant that are visible, the plumule staying 

 dormant until next spring. This type is known from several 

 other plants, and Miss Sargant has given quite a comprehensive 

 list of these, from which the following may be enumerated: 

 Several species of Anemone, Trollius, Eranthis, Delphinium 



* A similar case has been observed and described by Hill in geophilous 

 species of Peperomia. 



