THE EFFECT OF MANGANESE ON PINEAPPLE PLANTS, AND 
THE RIPENING OF THE PINEAPPLE FRUIT. 
THE EFFECT OF MANGANESE ON PINEAPPLE PLANTS. 
INTRODUCTION. 
The pineapple belongs to the family Bromeliacea?, several species 
of which are of epiphytic habit. With the exception of the black 
moss of the South which, as its name indicates, has a moss-like habit 
of growth and small terete branches, the members of this family 
which we have been able to examine show very similar structure and 
arrangement of the cellular tissue of the leaves. The pineapple pre- 
sents certain peculiar habits of growth which constantly remind one 
of the fact that it belongs to a family of plants in which a number of 
epiphytic species occur. The family as a whole occurs principally in 
tropical and subtropical climates and exhibits a power of adaptation 
to a wide range of conditions of soil and rainfall. 
The studies reported in this bulletin were undertaken jointly as a 
continuation of the work reported by this station regarding the effect 
of manganese on pineapples, and also regarding some of the points 
which have been observed in the chemical composition of pineapple 
fruits in different stages of development. 1 It will be noticed in study- 
ing the results which we have obtained that the anatomical and 
chemical findings are in remarkable harmony and that they mutually 
assist in explaining each other. 
PINEAPPLE ROOTS. 
One of the points which is likely to appear most striking in the 
study of pineapples in the field is the great variation in the root 
structures. Under favorable conditions the roots may be several feet 
in length and may quite fully occupy the soil in all directions from 
the base of the plant. In pulling up apparently vigorous plants, 
however, many will be found to have almost no root system, although 
the aerial portion of the plant appears to be as vigorous as those 
which possess a well-developed set of roots. Moreover, it is also a 
striking fact that even on many of the most healthy plants the roots 
may be nearly all dead and in process of decay, with only here and 
1 Hawaii gta. Bui. 26 ; Press Bui. 23^ Rpt. 1909, pp. 58-63; Rpt. 1910, pp. 41^3, 45-50. 
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