Genus Isodendrion — St. John 
215 
stamens free; the connective produced into a 
scale or prickle and with a dorsal honey gland 
at the base; and flowers axillary, solitary, or 
in few-flowered fascicles. 
It is agreed that Melchior had good reason 
for placing Isodendrion alone in a distinct sub- 
tribe, but he implied by his placement in his 
natural key that it was related most closely to 
the subtribe Rinoreinae. For the reasons given 
above, we disagree in this. Rather, it seems 
most closely related to Melicytus in the Hy- 
menantherinae. 
Parenthetically, the comment can be made 
that although Melchior (1925: 355-356) lists, 
as the important special literature, the treat- 
ments by Gray, Hillebrand, Leveille, and 
MacCaughey, he, too, omits the one by Heller 
and his very distinct species I. subsessili folium. 
Melchior accepts only the three original spe- 
cies of Gray and 1. Fauriei Levi., oblivious of 
the fact that the latter is based on a specimen 
of a well-known species of Gouania (Rhamna- 
ceae) . 
Distribution 
The 14 species of Isodendrion are distributed 
unequally between the larger Hawaiian is- 
lands. Luckily all of the collections include 
the name of the island in the data, even 
though two thirds of the collections were 
made before 1871. Such records cannot be 
placed precisely on a map. However, each is 
shown on the map (Fig. 15) by a circle on a 
likely part of the island. The precise localities 
known for the more recent collections are 
indicated by black discs. For the island of 
Maui, the evidence has vanished. Hillebrand 
(1888: 18) listed two of his own collections 
from Olowalu and Wailuku. These are be- 
lieved to have been destroyed in the bombing 
of Berlin in 1943. No duplicates of these two 
numbers have been found in any other her- 
baria, so the Maui records are now lost. In 
1914 Rock found a single Maui sheet in the 
Berlin Herbarium, with the data ”S. ridge of 
Wailuku Valley, West Maui, Aug. 1870, 
Oloalu or Valley of Waihee.” He noted that 
the leaves from the Waihee, West Maui, plant 
are much larger than the others. There is no re- 
cord from the now-denuded island of Kaho- 
olawe. Isodendrion has been found on all the 
other large Hawaiian islands. Kauai has three 
species, Niihau one, Oahu six, Molokai one, 
Lanai one, and Hawaii two. It will be seen that 
the largest numbers are on Oahu and Kauai, 
and that the three northernmost islands — 
Kauai, Niihau, and Oahu — have 11 of the 14 
species. The larger northern islands are con- 
sidered to be of greater geologic age than the 
others. 
Zonation 
The vegetational zones are well marked in 
the Hawaiian Islands, and it is of interest to 
consider the zonation of any new species. For 
the species L hawaiiense, I. lanaiense, 1. Lyd- 
gatei, I. molokaiense, and 1. Remyi, there is no 
zonal information, due to the lack of precise 
locality data. The vegetational zones of Rip- 
perton and Hosaka (1942) are used here. In 
Zone B is the locality for 1. Hosakae, and 
probably that of L Lydgatei. In Zone C 1, are 
the stations for 1. Forbesii, 1. laurifolium, 1. 
longifolium, L pyrifolium, 1. subsessili folium., and 
/. waianaeense. In Zone D 1 is the station for 
1. maculatum, which is at an elevation of 800 
feet in woods in the deep narrow gulch of 
Hanakapiai on the moist windward coast of 
Kauai. The others, listed above for Zones B 
and C 1, are in a region of dry scrub probably 
once forested with an open dry forest or in 
the slightly higher localities that are still 
covered with a dry forest. These lowland, or 
”kula,” lands were overrun by feral cattle 
soon after 1782 and, as a result, the native 
forest was largely destroyed. During the last 
two or three generations, cattle pasturing has 
been controlled, but on these semiarid lower 
slopes and ridges the grazing has been con- 
tinuous and heavy. Grazing during these two 
periods has resulted in the almost complete 
destruction of the plant species native to these 
lowland regions. 
The rarity of the species of Isodendrion is a 
