SEEDS AND SEED SUPPLY. 23 



Mich.) between the middle and the end of the month. The staminate flowers are borne laterally 

 on the shoots of the season (PL VI, l). They are extremely simple in structure, consisting of 

 numerous pollen sacs borne in pairs on the outer face of the scale-like staminal leaves. The 

 pollen is produced in great abundance and is carried by the wind to great distances. Fertilization, 

 however, notwithstanding the profuse production of pollen, often fails to take place. In fact, 

 failure appears to be rather the rule than the exception, if we consider the frequency of " oft' 

 years," in which little, if any, good seed is produced. But doubtless other causes often combine 

 to prevent the production of a full crop of seeds. 



The pistillate flowers occupy the apex of the young shoot (PI. VI, ), finally forming a bunch of 

 cones pendent from the ends of the branches. At the time of pollination they are about one- 

 fourth of an inch in length and have the appearance of minute fleshy cones, which by the end of 

 the first summer's growth have attained the length of three fourths of an inch to an inch, and 

 have the appearance represented in PI. VI, 3. They are not ripe until the fall of the succeeding 

 year, when the cones, having now attained their full size, as shown in PI. VI, 5 and 6, open and 

 allow the winged seeds to escape. In order to prevent loss of seeds it is necessary to gather the 

 cones a little before they ripen, which occurs during early September in most localities of the 

 natural range. Afterwards, if kept in a dry place, they will open readily themselves and allow 

 the seeds to fall out. The ripening is signalized by the change of color to a yellow brown and the 

 forming of a resin coat. 



SEEDS. 



The seeds are one-fourth of an inch in length by about half that measure in breadth, of an 

 oval form, grayish-brown in color, sprinkled with darker spots, and provided with a thin, delicate 

 wing, by means of which they are disseminated through the agency of the wind (PL VI, 8). The 

 seed coats consist of a hard outer shell, or testa, inside of which is a thinner membrane, the 

 endopleura. Inside of the seed coats is the whitish endosperm,' constituting the food" of the 

 germinating plant, within whichj occupying the center of the seed, is the small, straight embryo, 

 the three parts of which, stem, radicle, and cotyledons, are plainly distinguishable. 



To get 1 pound of seed from 2 to 2 bushels of cones are necessary. 



Concerning the production of seed, the experience in this country is but fragmentary. The 

 individual tree begins to bear quite early. Isolated specimens, or trees in open groves, bear cones 

 before they are twenty years old, and even trees in the dense forest seem to bear generally before 

 they are forty years of age. The capacity to bear abundantly is retained to old age, the oldest 

 trees seen still bearing heavily, and even mutilation by fire or otherwise does not prevent the trees 

 from bearing. 



EXPLANATION OK PLATE VI. 



1. Staminate flowers of Pinna strobiu just before shedding of pollen. 



2. Pistillate flowers, terminating young shoot. 



3. Young cones in autumn of first year. 



I. Young cones early in summer of second year. 



5. Cones at close of second year's growth before opening of scales. 



';. Mature cone, the scales separated to admit of dissemination of seeds. 



7. Single scale, showing outer surface. 



8. Single scale, showing inner surface with seeds in place. 



k 



SEED SUPPLY. 



A full crop of seeds is usually produced by the same tree only at intervals of several years. 

 Cones may be formed year after year, but upon examination it is often foundthat many of the 

 seeds are abortive, joi a large number of cones gathered at Ann Arbor, Mich., in 1886, not a 

 single one showed a perfect seed. Mr. John E. Hobbs states that the same year (188C) was a good 

 seed year in Maine, and that trees had not produced so largely before since 1879. According to 

 Mr. J. Dawson, of the Arnold Arboretum, a crop of seed may be looked for about once in five 

 years, though others make intervals between seed years shorter. The frequency of seed years has 

 not been sufficiently noted as yet to warrant any general statement, but it is known that during 

 certain seasons the seed production is perfectly general over large areas, while in other years it 

 is not. Thus, in 1897 the White Pine bore heavily in every pine county in northern Wisconsin. 



