THE MIDDLE FOREST ZONE. 
Next to the xerophytic forest on the leeward sides of the various islands, 
the middle forest region is one of the most interesting, as it is here that certain 
plant families, such as the Campanulaceae, tribe Lobelioideae, and Labiatae, as 
well as Rutaceae, reach their best development and become highly specialized. 
As is the case with the lower forest regions on the various islands, in re- 
gard to non-uniformity, so it is with the middle forest region, but still more 
pronounced as the various islands are of different ages, Kauai being the oldest. 
Owing to the fact that there is no typical forest for all the islands as far 
as the middle forest zone is concerned, it will therefore be of greater interest 
and value to describe the vegetative formations of this particular region on 
each island separately. 
The Island of Kauai is almost orbicular in outline and is intersected on the 
leeward side by a large canyon and several valleys, of which Kalalau, Miloli and 
Olokele are the most noteworthy. 
At 3800 feet elevation Metrosideros polymorpha (Ohia lehua) is a very com- 
mon tree and inhabits the outskirts of the middle forest zone. It is, however, 
associated with Siderorylon sandwicense (Alaa), Tetraplasandra Waimeae, the 
lauraceous Cryptocarya Mannii, previously thought to be peculiar to Kauai, but 
since found by C. N. Forbes on the Kaala Mountains on Oahu, Xanthoxylum 
dipetalum var. y., Broussaisia arguta, usually found along streams with the 
lobeliaceous Cyanea leptostegia (Hahalua), a truly superb plant of palm-like 
habit which reaches sometimes a height of 40 feet. It is associated with Cyanea 
hirtella, and Cyanea spathulata, both of which are shrubs with small flowers. 
Santalum pyrularium, the Kauai Sandalwood, forms an important tree of this 
region, while Elaeocarpus bifidus (Kalia) forms about 30 per cent. of the forest, 
following immediately after the Ohia lehua. This particular elevation has still 
some species of the lower forest zone present, as can be seen by the occurrence 
of Pterotropia Kauaiensis, Osmanthus sandwicensis, Antidesma, and others; 
while, as we enter the interior of the island, a wealth of foliage is displayed 
which can hardly be equaled anywhere in the group. 
Members of the Rutaceae are the most prominent, besides Pittosporum, of 
which P. Kauaiensis, P. acuminatum, and P. Gayanum, a species new to science, 
are of interest. The latter species occurs only on the high plateau at the 
foot of Mt. Waialeale, where the rainfall is immense. As already mentioned, 
the family Rutaceae is well represented in this floral zone. The genus Pelea, 
which has a few species in the drier regions, has not less than 14 or 15 species 
here, 10 of which are peculiar to Kauai, in the middle forest zone. They like 
heavy, gray, loamy soil, where water is often stagnant, forming small pools all 
the year round. Pelea cruciata (Piloula), and P. microcarpa (Kolokolo Moki 
hana), both recently deseribed species, are quite common in company with Wik- 
stroemia sandwicensis var. furcata (Akia), Pelea Kauaiensis, P. Knudsenii, P. 
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