762 MINNESOTA BOTANICAL STUDIES. 



mountain of Haleakala, 10,000 feet high. The slope of this 

 mountain, at lea,st on the western side, is easy and gradual. 

 The immense extinct crater of Haleakala — "House of the Sun" 

 - — is the largest in the world. It is triangular in shape, and 

 from 1,000 to 2,000 feet deep. 



Kahoolawe, southwest of Maui, is a small, barren island. 

 devoted to sheep raising, and has never been considered of 

 much interest botanically. 



Last, but not least, for it is the largest, is the island of 

 Hawaii, from which the group derives its name. It is 100 

 miles long and 90 miles wide. The northern end is occupied 

 by the Kohala range of mountains, with a height of 6,000 feet. 

 The remainder of the island is composed of three peaks, Mauna 

 Kea, 13,805 feet high; Mauna Loa, 13,675 feet, and Hualalai, 

 8,273 feet. These three mountains form the three points of an 

 equilateral triangle, with an elevated plateau of from 5,000 to 

 6,000 feet between them. On the southeastern slope of Mauna 

 Loa, at 4,041 feet, is the famous crater of Kilauea. 



Considering their proximity to the Equator, the Hawaiian 

 islands enjoy an unusually mild climate, the mean annual tem- 

 perature at Honolulu being about 79° F. The minimum is 50° 

 F. and maximum 90° F., but the latter figure is rarely reached. 

 The northeast trade winds, which blow during about three- 

 fourths of the year, are the cause of the pleasant and equitable 

 temperature. During the winter months, when the wind shifts 

 to the south or southeast, bringing with it some of the equa- 

 torial heat and sultriness, is the most disagreeable time of the 

 year. This is the season, too, when the heavy "Kona" storms 

 of wind and rain usually make their appearance. 



The topography has much to do with the rainfall, as the 

 islands are practically all mountains, with very little low land 

 along the coast. In nearly all cases a mountain barrier being 

 presented to the prevailing wind, the moisture is condensed, 

 and a heavy precipitation follows on the windward side, while 

 the lee side may be comparatively rainless. At Hilo, on 

 Hawaii, and at Hanalei, on Kauai, the average rainfall is 180 

 inches, while at points opposite on the lee sides of the same 

 islands, the average is about 25 inches. 



As the soil is composed of disintegrated lava rock, it is very 

 porous, and very little water can be found on and near mount- 

 ain summits, although there are exceptions on Maui and Kauai, 

 where bogs have been formed. Usually the rainfall which is 

 precipitated on the summits and upper slopes, percolates. 



