512 
PACIFIC SCIENCE, Vol XIX, October 1965 
ing, sometimes attaining a height of 50 feet 
and a spread of 60 feet. The branchlets are 
usually dark colored, although not quite so dark 
as those of M. ternifolia. The young leaves on 
new growth are generally flushed with red or 
pink coloration. Occasional trees may be seen, 
however, which lack anthocyanin pigmentation 
and, consequently, have new leaves which are 
pale yellowish green in color. Juvenile leaves 
are long, linear-lanceolate. Adult leaves differ 
little from juvenile leaves except in being some- 
what broader (Fig. 3C). Adult leaves measure 
4-20 inches in length and 1-3 in width. They 
occur most commonly in whorls of four, al- 
though an occasional branch may have three 
or five; and, in young seedlings, they generally 
occur in opposite pairs. The racemes are borne 
in the proximal axils of the most recently 
matured two or three increments of growth. 
The racemes vary from 6-18 inches in length, 
and the number of flowers from 100 to 300 
(Fig. 1). In the vast majority of trees the flow- 
ers are bright pink. In the occasional individuals 
which lack anthocyanin, however, they are white 
or cream colored. The crop matures from March 
to June in Australia, from March to June in 
Hawaii, and from September to January in 
California. There is no tendency toward ever- 
bearing in this species, consequently the entire 
crop is seasonal. 
This species, as noted previously, was not 
recognized as new and different from M. terni- 
folia until 1954, when it was so recognized by 
Johnson (1954:15). By this time it had been 
in cultivation, as M. ternifolia, for 84 years. 
There is little doubt that it is the one referred 
to by an anonymous writer in 1870. Its intro- 
duction into commercial orcharding occurred 
about 1890, with the planting of about 250 
trees on the K. C. Fredrickson property at Rous 
Mill, N.S.W. I visited this orchard, which is 
still in production, in I960. The species was 
introduced into Hawaii by the Board of Agri- 
culture and Forestry of the Government of Ha- 
waii in 1892-94 for use in reforesting the 
slopes of Mt. Tantalus back of the city of 
Honolulu (Pope 1929:2). There seems to be 
no record of when and by whom it was intro- 
duced into California. The oldest trees I have 
seen appear to be 50-60 years old. They occur 
only in San Diego, Orange, and Los Angeles 
counties in southern California. 
CYTOLOGY AND GENETICS 
All three species have the identical somatic 
chromosome number of 2n = 28. Insofar as I 
know, this report is the first on the chromo- 
some numbers of M. ternifolia and M. tetra- 
phylla. I determined these numbers from root 
tips of M. ternifolia and M. tetraphylla seed- 
lings, and from dividing microsporocytes in 
M. tetraphylla. 
The chromosome number of M. integrifolia 
was first reported (Darlington and Wylie, 
1955:90) as "2n = 28 (56),” as a previously 
unpublished number determined by Ukio Urata 
of the University of Hawaii. The 56 in paren- 
theses refers to a clone, Y-279, which was dis- 
covered to be tetraploid. Later, Urata (1954: 
12) published the numbers as "n — - 14 and 
n — 28,” under an old, lapsed synonymous 
name, M. ternifolia F.v.M. var. integrifolia 
(Maiden and Betche) Maiden and Betche. I 
am familiar with Urata s material, since I served 
on the committee for his Master of Science 
thesis which served as the basis for the pub- 
lication cited. The chromosome number re- 
ported for this species is confirmed in a recent 
paper by Ramsay (1963:9). 
Johnson (1954:18), Beaumont (1956:17), 
and Smith (1956:40), have pointed out that 
a number of trees occurring in the Numinbah 
Valley and in tributary valleys of the Coomera 
River in southernmost Queensland have char- 
acters which strongly suggest that they are hy- 
brids between M. integrifolia and M. tetra- 
phylla. The region in question is the one in 
which the ranges of the two species come to- 
gether and overlap to some degree. Beaumont 
collected cuttings of several specimens in 1953, 
which he sent to Hawaii and California to be 
propagated. These have flowered and fruited in 
recent years and, from close observations on 
them, there seems to be every reason to believe 
that they are indeed hybrids. Meanwhile, simi- 
lar trees have been found in Hawaii and Cali- 
fornia among seedlings produced from seeds 
collected in orchards where the two species 
