GERMINATION OF BLUEBERRY SEEDS. 



53 



Fig. 19. — Section of a blue- 

 berry seed : a, Embryo ; h, 

 endosperm : c, outer seed 

 coat. (Enlarged 18 diame- 

 ters.) 



ticularly evident when germination begins, for many of the seeds 

 have been washed to the surface in the process of watering and have 

 germinated Avithout any soil covering. It may be several days before 

 the root penetrates the soil, but the moisture maintained in the air 

 underneath the glass keeps these naked seedlings from death by dry- 

 ing. After germination has progressed so far that a good stand 

 of seedlings is assured the glass should be 

 gradualh^ removed. 



Tlie flats seeded on August 12, 1908, were 

 kept in a greenhouse as cool as practicable 

 and shaded from the sunlight. "When 

 started in winter, seed flats should be kept 

 at a temperature not less than 50° to 60° F, 

 at night and about 15 degrees higher in the 

 daytime. Under such conditions sunlight 

 during the whole day seems to benefit them. 

 Germination began on September 18, 

 thirty-seven days after seeding, and con- 

 tinued for more than two months. In other seedings of this and the 

 closely related blueberries known as Vacciniiim atrococeum and F. 

 pallichim^ germination has begun in as short a period as twenty-five 

 days. This slowness of germination might be considered merely a 

 feature of the general sluggishness of growth in these plants. It is 

 in fact, however, due to a much more specific cause. The food stored 

 in the seed for the nourishment of the plantlet is not located in the 



cotyledons, as in the bean or pea. 

 for example, but it lies in a mass 

 called the endosperm, quite outside 

 the embryo. (See fig. 19.) It re- 

 quires several weeks for the minute 

 embryo, feeding on the large mass 

 of surrounding endosperm, to grow 

 to sufficient size to burst open the 

 seed coats. Until the embryo has 

 attained such size it is physically 

 impossible for the seed to ger- 

 minate. 



When the seedlings had straightened themselves out they were 

 about 0.2 to 0.3 of an inch (5 to 8 mm.) high and the newly expanded 

 cotyledons about O.OG of an inch (1.5 mm.) long. (See fig. 20.) 

 Within a few days the first foliage leaf began to appear between the 

 cotyledons about 0.06 of an inch (1.5 mm.) long. (See fig. 20.) 

 inch (10 to 15 mm.) high, the erect unbranched stem bearing four 

 or five foliage leaves, and the cotyledons having expanded to a length 

 of 0.12 of ail incli {?> mm.). (See fig. 21.) 



Fig. 20. — Blueberry seedlings in the coty- 

 ledon stage : a. Before the expansion of 

 the cotyledons ; b. at the beginning of 

 the development of the first foliage 

 leaf. (Enlarged 2 diameters.) 



