Hybridism in the New Zealand Flora 115 
habit of M. ephedroides but is far more leafy. Mr B. C. Aston first 
suggested to me that it might be a hybrid. 
3. Hybrids between species of different, but considerable, lati¬ 
tudinal range, which, from a definite point, grow in close proximity 
for a certain distance. 
The number of hybrids in this class is 30; the following are 
instructive examples. 
(a) Melicope simplex x ternata (== M. Mantellii Buch.). Accepted 
by T. Kirk as a hybrid in The Student's Flora of New Zealand, 
p. 86. 
Both species belong to rain-forest. M. simplex is an erect, twiggy 
shrub with small 1-foliate leaves and small flowers, 1-3 on each 
peduncle, and M. ternata a small, bushy tree with fair-sized 3-foliate 
leaves and larger flowers in panicles. The hybrids exhibit every 
transition in habit, leaf and flower between the two parents. 
M. simplex extends from north to south throughout the lowland 
belt of both islands, but M. ternata halts a few miles to the south of 
latitude 42 0 . From the extreme north of the North Island south¬ 
wards to the above line the hybrids are common, but further 
south there are none. So, too, on the Kermadec Islands where only 
M. ternata occurs. 
(b) Myrtus bullata x obcordata (= M. Ralphii T. Kirk). Treated 
as a hybrid by L. Cockayne in Trans. N.Z.Inst., 50, pp. 179-83, 
1918. 
Not only was M. Ralphii not considered to be of hybrid origin, 
but in the Manual, p. 169, there is no hint of its polymorphy. Never¬ 
theless, as I have shown from an examination of many specimens 
and observations in different localities, there are transitional forms 
of every kind including almost pure M. bullata and almost pure 
M. obcordata. The former species is common in rain-forest, and its 
outskirts, throughout the lowland belt of the North Island, but it 
halts somewhat to the south of latitude 41 0 ; the latter species 
extends from the south of the South Island almost as far as 
latitude 35 0 in the North Island. At the southern limit of the range 
of M. bullata the hybrids suddenly appear and they continue north¬ 
wards, so far as is known, wherever the two parents come together. 
Although M. bullata is common in the far north of the North Island, 
M. obcordata has been observed only in the one locality (Reef Point) 
which forms its northern limit. Here M. bullata is also present and 
8—2 
