58 



MORPHOLOGY OP ANGIOSPERMS 



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

 sporium to the single hypodermal cell that terminates the axial 

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



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

 Astilbejaponica, x 550; after Webb." C, Salix glaucophylla, x 600; after Cham- 

 berlain. 36 D, Rosa livida, x 224; after Strasburger. 13 £, Alchemilla alpina, 

 x 275 ; after Murbeck. 67 F, Callipeltis cuctdlaria ; after Lloyd. 81 G, Quercus 

 veluUna, x 720 ; after Conrad. 63 



highly specialized groups in reducing the nucellus within 

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

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

 (Lloyd 61 ), 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 (Fig. 

 23). In 1870 Strasburger 13 described the several-celled ar- 

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

 similar archesporium in Geum, Sanguisorba, Agrimonia, Ru- 



