260 



EMBRYOGENESIS IN PLANTS 



process which pierces the integument in the micropylar region and 

 eventually enters the pericarp. A second haustorial body — the 

 placental haustorium — also arises from the basal cell group, grows 

 through the integument and funiculus, and penetrates to the point of 

 entry of the vascular strand of the raphe (Walker, 1947). 



Fig. 65 



A-D, Embryogeny in Myriophyllum alterniflorum. Note the enlarged synergid-like 

 suspensor cells. E-M, Embryonic development in three genera of the Fumariaceae. 

 E, F, Hypecoum procumbens. Extensive development of the suspensor cell which 

 does not divide; when the apical cell divides, the cell next the suspensor also 

 becomes greatly enlarged; together these two haustorial cells have a synergid-like 

 appearance. G, H, J, Corydalis lutea. The basal cell undergoes a number of free 

 nuclear divisions, but remains undivided; products of the apical cell contribute to 

 the suspensor. K, L, M, Fiimaria officinalis. The nuclear divisions in the basal cell 

 {cb) are accompanied by wall formation. All the products of this cell, and some 

 from the apical cell (cw), contribute to the suspensor (after Soueges). 



In general, in the Scrophulariaceae, (which may be selected as an 

 advanced gamopetalous family), the embryo itself does not show any 

 especially unusual features: it is initially filamentous and later consists 

 of a typical multicellular distal region and an elongated suspensor. 

 The post-fertilisation phase is, however, attended by developments of 

 a rather remarkable kind. These have been the cause of some con- 

 troversy since the days of Hofmeister (1858). In the ovules of Minndus 

 tigriuus and Toreniafournieri a single integument surrounds the nucellus 

 which soon breaks down except in the chalazal region (Guilford and 



