".] MONOCOTYLEDONOUS DICOTYLEDONS 95 



Ranunculus Ficaria, the lesser Celandine, is 

 descended from an aquatic ancestor. It has 

 lost one of its cotyledons. Miss Sargant notices 

 that the slow maturation of the embryo in the 

 seed of this plant is comparable with " the slow 

 germination of many monocotyledons." 1 It 

 may be added that the subsequent phyllotaxis 

 is distichous, like that of a monocotyledon ; and 

 is followed by a ternary calyx and eight or nine 

 petals ; f ths bring a nearer angular distance (135) 

 to 1 (120) than fths (144). If there be 9 

 petals, these are obtained from 3 whorls + 1. 2 

 This plant is, therefore, a true monocotyledon, 

 but betrays its origin by its floral affinities with 

 other species of Ranunculus. 



It has been observed in water-lilies that the 

 embryo is at first pear-shaped. There is then 

 formed a " cotyledonary ridge," at first one-sided ; 

 from this the cotyledons arise. This ridge may 

 perhaps be the first indication of a sheathing 

 petiole, so characteristic of aquatic dicotyledons, 

 as in Ranunculacece, Umbelliferce, etc., and in 

 all monocotyledons. 8 



figures of Tamus communis, showing the development of one cotyledon 

 and the arrest of the other, Sot. Zeit. 1878, Taf. iv. figs. 21-25. 

 Illustrations of the " absorbing" organ will be found in Ann. Jard. 

 Botan., Buitenzorg, vol. ix. 1890-91, pi. xvi. fig. 5ff. of Elattaria 

 Cardamomum. 



1 " Theory of the Origin of Endogens," etc., p. 84. 



2 ' ' Origin of Di-trimerous Whorls in Dicotyledons," Trans. Lin. 

 Soc. 2nd ser., Bot. vii. p. 153. 



3 "The Embryogeuy of Some Cuban Nymp}usace<e," by M. T. 

 Cook, Hot. Gaz., vol. xlii. p. 376 (November 1906), pis. xvi.-xviii. 



