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 44 FACTS ABOUT CROP TREES

with limestone. This richness of the fresh unleached lava soil of Hawaii should be kept in mind when one thinks of applying Hawaiian facts to many other areas of semi-arid frostless lands in which the algaroba may probably find a suitable climate.™* (See further discussion of this point in Chapter VIII on The Mesquites.)

The Hawaiian keawe seems truly tropical, but the genus to which it belongs is by no means limited to lands without frost. (See the findings of Dr. Walter S. Tower in the next chapter.)

The surprising performances reported in this chapter may almost without exception be said to be products of wild trees, although the process of thinning out may sometimes leave the better ones. It should be noted that nine thousand acres of trees on the sugar plantation mentioned above were scattered by cattle from one chance tree at the windmill. What a shame that it was not an exceptionally good tree!

There is every reason to think that the keawe produced by chance is capable of much improvement by selection and breeding. Then the propagation of orchards from the best trees should give a still better crop than is at present obtainable.

The chief value of the keawe in this book is that it is an example—a successful tree crop in a world that needs many other tree crops to fit particular places and keep its scanty soil upon its rocky ribs.

31"In Cuba, where I lived a number of years, one of the locusts, called a 'guasima,' furnishes considerable food for cattle, and they are introducing from the Hawaiian Islands a locust with a sweet substance in the pod as a food for horses, cattle, and swine. I believe this tree is called an algaroba." (Letter signed N. S. Mayo. Animal Husbandman. Virginia Agricultural Experiment Station. Blacksburg. Virginia. May 22, 1913.)

33 "There is a great difference in the yielding capacity of different trees. They begin to bear profitably at four or five years of age." (Letter signed E. V, ner. Agricultural Experiment Station. Honolulu. Hawaii. August 12, 1913.