202 



MORPHOLOGY OF ANGIOSPERMS 





and it is only late that the embryo becomes differentiated from 

 the massive suspensor (Fig. 94). 



In the Rubiaceae Lloyd 57, 85 has described a remarkable de- 

 velopment of the suspensor, which in many members of the group 



acts as a haustori- 

 ura (Fig. 95). In 

 Vaillantia hispida 

 the large suspensor 

 cells near the em- 

 bryo are clustered 

 like " a bunch of 

 grapes," while far- 

 ther down a single 

 elongated cell forms 

 a point of attach- 

 ment. In Asperula 

 the scanty cvto- 

 plasm and the nu- 

 cleus are found at 

 the distal ends of 

 the haustorial cells 

 of the suspensor, 

 recalling a condi- 



Fio. 95. — A, Vaillantia hispida. Young embryo showing 

 haustorial suspensor; x 375; alter Lloyd. 67 B, Aspe- 

 rula azurea. Young embryo with haustoria from sus- 

 pensor highly developed; after Lloyd. » 



tion which has been 

 described for root 

 hairs. It is worthy of note that among the Spermacoceae and 

 in Houstonia there is a complete absence of these striking- 

 adaptive characters of the suspensor. 



It is among the Leguminosae, however, that the greatest 

 amount of variation in embryogeny exists and the most unusual 

 forms appear, as shown by Guignard 21 (Figs. 96-98). It is 

 impossible to give in a brief account any adequate idea of the 

 amount of variation displayed by the nearly forty species Guig- 

 nard has described, involving in the main the character of the 

 proembryo and the final condition of the suspensor. In 1880 

 Strasburger 19 had called attention to the fact that the cells of 

 the very long suspensor of Lupinus separate early, leaving the 

 embryo free and some distance from the micropylar extremity 

 of the sac. This, however, is but one phase of the embryogeny 

 of the Leguminosae. In every case the first segmentation of the 



