200 



MORPHOLOGY OF ANGIOSPERMS 



<:est as wide a range of variation as among Monocotyledons, 

 though not so clearly related to great groups. 



In Geranium, as has long been known, while the Capsella 

 type is maintained in general, there is no hypophysis, the root- 

 tip being covered by the tissue of a massive suspensor. 



In Peperomia pellucida Campbell 56 and Johnson 62 have 

 both observed that the first segmentation of the fertilized egg 

 is vertical, followed bv a transverse division, and that there is 



7 V ' 



no indication of a suspensor. 



In Loranthus sphaerocarpus Treub 22 has described the first 

 division of the fertilized egg as vertical, as in Peperomia, but 

 followed by transverse divisions, so that the proembryo resem- 

 bles two filaments lying side by side (Fig. 91). The two basal 

 cells elongate enormously, forming a suspensor as in Gymno- 

 sperms, whose length is increased by the moderate elongation 

 of the second pair of cells, and which becomes more or less tor- 

 tuous, the cells twisting about one another. In L. pentandras 

 (Treub 26 ) the elongating suspensor early forces the embryo 

 against the resistant base of the sac. where it becomes much 

 flattened out, and for a time bears little resemblance to an em- 



A 



B 



Fig. 92. — Loranthus pentandrus. -4, young embryo advancing into endosperm; thick- 

 walled tissue at base of sae deeply shaded: e, embryo; g, suspensor: x 88 ; £. later 

 stajre. the embryo has reached the resistant base of the sac and has become flattened 

 out: x 144.— After Treub. 28 



bryo (Fig. 02). In Myoporum, as described by Billings. 70 the 

 suspensor is also extremely long and filamentous, forcing the 

 young embryo down into the principal mass of endosperm, 



