Polynesian Species of Myoporum — ^Webster 
find morphological characters sufficiently 
constant to distinguish them. 
Because of its great range of morphological 
variation, M. sandwkense poses a particularly 
difficult problem in species definition. In its 
most typical form the species is well charac- 
terized by its flowers with five stamens and a 
glabrous style, and by its whitish-colored 
drupes with five or more cells. To some ex- 
tent, however, every one of these characters 
proves to be inconstant when the complete 
range of variation of the species is ascertained. 
The other Polynesian species typically differ 
in having flowers with four stamens and 
pubescent styles as well as reddish-tinted 
drupes with fewer cells, but most of these 
characters are inconstant. However, M. sand- 
wkense not only approaches the other Poly- 
nesian species very closely, but also is hard 
to separate from M. tenui folium, a species 
lying to the west and southwest in Micronesia 
and Melanesia. This latter species is charac- 
terized by the small size of its flowers and 
fruits; but there are forms of M. sandwkense 
whose reproductive organs are of about the 
same dimensions. Of course, in all these cases 
species distinctions can be maintained by 
using rather complicated combinations of 
characters; for instance, Af. tenuifolium can 
be separated from M. sandwkense by the fact 
that the forms of the latter which have small 
flowers and fruit do not have pink-tinted 
drupes. Such contrived species differences are 
admittedly unsatisfactory, but they will have 
to serve for the present. The temptation to 
combine various of the insular species should 
be resisted until the entire group is surveyed, 
because only then will it be possible to define 
the exact limits of M. sandwkense and its 
nearest congeners. 
Because the classification of the insular 
myoporums is still in a very imperfect state, 
one hesitates to speculate as to the phylogeny 
of the Polynesian groups. However, the fol- 
lowing observations on the possible relation- 
ships of the Hawaiian groups seem worthy 
of statement. 
57 
It is pretty clear that the group of M. 
sandwkense showing the greatest resemblance 
to the Austral Island species is ssp. Wilderi, 
although it is not possible to say whether or 
not the latter originated directly from or 
coordinately with the Austral Island species. 
Among the groups of Af. sandwkense from 
the Hawaiian Islands proper, var. Fauriei 
shows the greatest resemblance to ssp. 
Wilderi. Because var. Fauriei is restricted to 
the island of Hawaii, it seems likely that this 
island was the point of immigration of 
Myoporum. Degener (1930: 266), on the basis 
of the occurrence of pubescent, serrate leaves 
on certain wounded plants from Molokai, 
has suggested that the direct ancestor of the 
Hawaiian forms had leaves of this type. How- 
ever, this phenomenon does not seem to be 
a case of a reversion to an immediate ances- 
tral type, but rather the expression of a 
potentiality which is widespread, inasmuch as 
independent occurrences of pubescent leaves 
are known from other Hawaiian islands as 
well as from Australia, New Zealand, and 
New Caledonia. 
It seems evident that var. sandwkense, the 
most widely distributed of the Hawaiian 
groups, is derived from var. Fauriei, while 
it in turn has given rise to varieties lanatense, 
Degeneri, and stellatum. The origin of ssp. 
St.-Johnii is more obscure. It could have come 
directly from the adjacent population of var. 
Fauriei, but the rather great morphological 
differences between the two entities make 
this rather questionable. The history of 
Myoporum on the island of Hawaii is made 
even more mysterious by the fact that var. 
sandwkense is absent from this island, even 
though it is presumed to have originated 
there. This suggests that the original popu- 
lation of var. sandwkense on Hawaii has 
become gradually modified into the group 
now known as ssp. St.-Johnii. This suggestion 
is of course hypothetical, but it would explain 
the curious anomaly of the absence of var. 
sandwkense from its presumed place of origin, 
as well as the occurrence on Hawaii of forms 
