

Fig. 37. Embryogeny in Piniis 



A-E, P. lambertiana. A, First division office nuclei. B, Three-tiered proembryo. 

 C, Four-tiered proembryo. D, Two of the four primary embryos have delimited the 

 primary suspensor initials. E, Primary embryos delimiting third segments. F-J, 

 P. ponderosa. F-J, Four successive stages in the development of the young embryo. 

 K, P. nigra. Older embryo, with apical cell. L, P. radlata. Median l.s. of mature 

 embryo. (A-E, x 160; F-J, x 120; K, x 95; redrawn from Johansen.) 



