A New Method of Germinating Acorns for 



Forest Planting 



Bv John W. Harshberger, University of Pennsylvania 



THE trained forester is always alive to new methods 

 by which the objects of his profession may be 

 reached by the easiest and most satisfactory 

 methods. An important question to the forester is the 

 collection, preservation and germination of the fruits and 

 seeds collected by him to establish his forest nursery, and 

 the methods adopted by him toward this end have been 

 elaborated in great detail. The proper preservation of 

 nuts, acorns, other seeds and fruits over winter has always 

 been a difficult matter, for the germination of the seeds 

 must be kept unimpaired during the cold and frosty 

 period of the year. 



A new method of treating one class of these fruits, 

 acorns, was discovered in an accidental way by the writer 

 about two years ago, and a description of the method ma}- 

 prove of interest to the readers of American Forestry. 

 In order to acquaint myself with the method used by the 

 Pennsylvania forester, I wrote to Professor Joseph T. 

 Rothrock, of West Chester, asking him what method he 

 had used in the preservation of acorns over winter. In 

 reply he stated that his observations had been made on a 

 scale of but a few thousand. 



His method was as follows : ordinary strawberry 

 boxes were taken, holding one quart, and the acorns to 

 be kept over winter were placed in them, layers of almost 

 dry earth alternating with layers of acorns, until the boxes 

 were filled. These strawberry boxes, filled with acorns 

 and earth, were then put in a larger box, so that the 

 smaller boxes were piled one above the other. Over the 

 retaining box, a still larger box was turned upside down 

 as a cover, and over these boxes earth was shoveled until 

 they were entirely covered, so as to keep out rain and 

 cold. This cache was then opened in the spring and the 

 sprouting acorns were removed and planted. Dr. Roth- 

 rock also described a method of planting the acorns in 

 the fall, covering them with a layer of leaves, and just 

 enough earth to keep the leaves from blowing away. This 

 should be done in well-prepared ground, so that the seed- 

 lings can make a rapid growth in the spring. 



Guppy, an English botanist, has demonstrated that the 

 acorns of the red oak actually germinated on the tree, 

 thus showing vivipary, and this growth continued on the 

 tree after the pericarp, or fruit case, had commenced to 

 dry and lose weight. He demonstrated that ripe acorns 

 are able to proceed at once to germination, if placed under 

 conditions inhibiting the glazing of the fruit wall and the 

 drying of the fruit. On September 17, 1908, he collected 

 ripe acorns and placed them in damp moss in a warm 

 cupboard. They were still biologically connected with 

 their cupules, and their shells, though beginning to brown, 

 were still thick and moist. Within eight days he found 



some of them germinating normally, and one of them, 

 when planted, grew healthily under protection during 

 winter. He repeated this experiment with green, ripe 

 acorns, showing no signs of dying, and possessing, as in 

 the first case, entire shells. In five days half of them had 

 split their shells and in several the radicle protruded. 

 After havino- read this account, the writer found, on 



.\. Acorn of Black Jack oak. B. Acorn of Black Jack oak dissected. C. Embryo 

 Black Jack oak. D. First stage of vivipary in acorn of Black Jack oak. E, F. G, 

 Later stages of vivipary. H, I. Stages in germination of green acorns of Black 

 Jack oak. J. Stage in germination of green acorn of white oak. K. Detail of 

 the germination of the acorn of white oak. L, M. Germination of green unripe 

 acorns of white oak. 



September 5, 1912, a viviparous acorn at Spring Lake, 

 New Jersey, on the Black Jack oak. This state was prob- 

 ably induced by preceding heavy rains, followed by mists 

 and fogs. The examination of this acorn (Figs. A-G in- 

 clusive) showed that the embryo had swollen sufficiently 

 to crack open the acorn wall. This suggested experiments 

 with a number of acorns from American oaks to test 

 the discoveries of Guppy with reference to the germina- 



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