58 



MORPHOLOGY OF ANGIOSPKRMS 



mate. The prevailing habit, however, is to limit the arehe- 

 sporium to the single hypodermal cell that terminates the axial 

 row of the nucellus. This seems to have resulted in the more 



Fig. 23.— Longitudinal sections of ovules showing multicellular arehesperia. A. B, 

 Astilbe japonica, x 550; after Webb.™ C, tialix glaucophylla, x 600; after Cham- 

 berlain. 36 I>, Bom, Uvida, x 224; after Strasboeoek.is £,, Alchemilla alpina, 

 x 275; after Murbeok." F, Callipeltis cttcuUaria; after Lloyd." G, Quercus 

 velutina, x 720 ; after Conrad. 63 



highly specialized groups in reducing the nucellus within 

 the epidermis to this axial row, as LiJiiim, many Orchida- 

 ceae (Dumee 44 ), Lobeliaeeae (Marshall-Ward 14 ), Rubiaceae 

 (Lloyd 01 ), Compositae, and many other sympetalous groups. 

 In such cases the nucellus in longitudinal section shows only 

 three rows of cells. 



It is of interest to note the recorded cases in which the 

 archesporium is said to consist of more than a single cell (Fie;. 

 23). In 1879 Strasburger 13 described the several-celled ar- 

 chesporium of Rosa Uvida, and in 1880 Fischer 15 reported a 

 similar archesporium in Geum, Sanguisorba, Agrimonia Bu- 



