12 
NATURE 
[ Von. 4, 1869 
China, which does not discharge its pollen till considerably 
after the opening of the flower, and which never fructifies 
in this country. But a more striking instance is found in 
the “allspice tree,” the Chimonanthus fragrans, or Caly- 
canthus precox of gardeners, a native of Japan, which, 
B. Laiiium GaLroppoLon.—Pistil and stamens from open flower ; 
the latter discharging pollen. 
flowering soon after Christmas, has yet the most perfect 
contrivance to prevent self-fertilisation (Fig. C). In a 
manner very similar to that which has been described in 
the case of Parnassia palustris,* the stamens, at first 
nearly horizontal, afterwards lengthen out, and rising up 
perpendicularly, completely cover up the pistil, and then 
discharge their pollen outwardly, so that none can possibly 
fall on the stigma. As a necessary consequence, fruit is 
never produced in this country ; but may we not con- 
jecture that in its native climate the Chimonanthus is 
4 
C. CHIMONANTHUS FRAGRANS 
1. Early stage of flower, calyx and corolla removed. 
2. Later stage, stamens surrounding the pistil, and discharging their pollen 
outwardly. 
abundantly cross-fertilised by the agency of insects, 
attracted by its delicious scent, in a similar manner to 
our Grass of Parnassus ? 
The description detailed above cannot of course apply 
to those winter-flowering plants in which the male and 
female organs are produced on different flowers; but here we 
find commonly another provision for ensuring fertilisation. 
In the case of the hazel-nut the female flowers number 
from two to eight or ten in a bunch, each flower containing 
only a single ovule destined to ripen. To each bunch of 
female flowers belongs at least one catkin (often two or 
three) of male flowers, consisting of from go to 120 flowers, 
and each flower, containing from three to eight anthers. 
The pollen is not discharged till the stigmas are fully 
developed, and the number of pollen-grains must be many 
* Journal of the Linnean Society for 1868-69, Botany, p. 24. 
thousand times in excess of what would be required were 
each grain to take effect. The arrangement in catkins 
also favours the scattering of the pollen by the least breath 
of wind, the reason probably why so many of the timber- 
trees in temperate climates, many of them flowering very 
early in the season, have their male inflorescence in this 
form. 
The Exfhorbias or spurges have flowers structurally 
unisexual, but which, for physiological purposes, may be 
regarded as bisexual, a single female being enclosed along 
with a large number of male flowers in a common envelope 
of involucral glands. Two species are commonly found 
flowering in the winter, and producing abundance of 
capsules, Z. feplus and helioscopia. In both these species 
the pistil makes its appearance above the involucral glands 
considerably earlier than the bulk of the stamens.(Fig. D). 
D. Evpyorpta HELIOSCOPIA 
_ 1. Head of flowers opened, pistil and single stamen appearing above the 
involucral glands. 
2. The same somewhat later, with the stigmas turned upwards. 
A single one, however, of these latter organs was observed 
to protrude beyond the glands simultaneously, or nearly 
so, with the pistil, and to discharge its pollen freely on the 
stigmas, thus illustrating a kind of quasi-self-fertilisation. 
The remaining stamens do not discharge their pollen tilla 
considerably later period, after the capsule belonging to 
the same set has attained a considerable size. In £. helio- 
scopia the capsules are always entirely included within the 
cup-shaped bracts, and the stigmas are turned up at the 
extremity so as to receive the pollen freely from their own 
stamens. Now contrast with this the structure of £. azyg- 
daloides, which does not flower before April (Fig. E). The 
heads of flowers which first open are entirely male, 
containing no female flower ; in the hermaphrodite heads, 
which open subsequently, the stigmas are completely 
B = SW ° 
Me Rey 
( 6 
Fa bay 
(DS 
E, EvpHorsia AMYGDALOIDES.—Head of flower, pistil appearing above 
the involucral glands, all the stamens still undischarged. 
exposed beyond the involucral glands long before any 
stamens protrude from the same glands. Here, therefore, 
complete cross-fertilisation takes place, the pollen from 
