the extravagant hypothesis of M. Fillette de Clermont, who fancies that it is due to the
cohesion of 3 flowers.”—Lindley's Natural System o f Botany.
“ This genus only differs from the other Myrtaceae by having two verticels of carpels
developed instead of one, and perhaps in a truly wild state the upper or adventitious one may
occasionally disappear. The inner series (or those at the bottom of the fruit) have their
placentae in the axis ; but the outer series, forced to the top of the fruit by the contraction of
the mouth of the tube of the calyx, having their placentae in the ovary at the back of the
inner carpels, exhibit them in the ripe fruit in a horizontal position on the upper surface of the
lower cells.”—Arnott Encyclop. Brit. Ed. 7, et Prod. Fl. peninsula 1 Pg. 327.
Premising that the whole controversy turns on these questions, 1st, what is the true
structure of a Pomegranate ? and 2d, whether the difference between it and Myrtus is sufficient
to separate these genera as types of distinct orders ?
I shall now proceed to examine these conflicting statements and endeavour to ascertain on
which side the balance preponderates and whether indeed, there is not room for an explanation
different from any of these yet proposed.
Mr. Don’s description of this fruit on the strength of which he first proposed to remove
this genus from Myrtaceae, the order with which it was previously associated, as a distinct
family appears to me most unphilosophical and altogether untenable. He, as E understand,
considers the fruit a one-celled receptacle the centre of which is filled with a spongy placenta,
round the surface of which there are a number of irregular cells occupied by clusters of ovules:
but he does not tell us how the central placenta got there neither does he account for the
ovules being attached to the parietes of the cell and not to the central placentas.
H is whole description in fact proves that it had been drawn up from inadequate examination
and that he, at the very time he is accusing all authors of overlooking the real structure of
this fruit, totally misapprehends it himself, as we shall by and by see.
DeCandolle gives a more correct description of it when he says that it consists of two
chambers, the under 3*celled, the upper from 5 to 9-celled, with the placentas of the upper cells
reaching from the parietes to the centre while those of the lower division proceed irregularly
from the bottom of the fruit. He does not however assign this peculiar structure as his principal
reason for viewing the order as distinct from Myrtaceae, but has recourse to others in my
estimation of minor importance.
Lindley conceives that there are two rows of carpels, three or four of which surround the
axis at the bottom, while the remainder surround these and occupying the upper part of the
fruit adhere to that part of the tube of the calyx. The placentas of these upper carpels he
conceives contract an irregular kind of adhesion with the back and front of their cells. The
meaning of this is far from being clear to me, but if it means that he considers the placentas
of the upper as well as the lower row to proceed from the axis towards the circumference to
which last they contract accidental adhesions, then he takes an erroneous view and if the
examples quoted in illustration support this view, they are not in point as regards the structure
of Punica.
Mr. Arnott like Lindley views the fruit as consisting of two rows of carpels, an outer and
inner, the former of which he thinks may be adventitious. To understand his theory we must
first suppose the tube of the calyx spread out as a flat surface and covered with two circles of
carpels, the inner next the axis and the outer occupying a larger circle beyond. That the
margin of the calyx then contracts so as to turn the outer series over the inner. According to
this supposition, the attachment or base of the placentas of the outer series should be in the
circumference and the apex in the centre, while that of the inner should be in the opposite
direction, that is, have the base in the centre and the apex towards the circumference, an explanation
which is in accordance with what we find, except in so far as it does not account for the
horizontal partition between the two series, nor can I exactly understand on what ground we
are warranted in assuming that the outer series is adventitious and the result of cultivation, as
it has every where been found so constant in all circumstances. But be that as it may, this
theory certainly accounts for the crossing of the placentas in the two rows, which we so invariably
find, whether correctly or not cannot be determined until we get fruit with a single row of
carpels, which has not yet been found.
These explanations, which I venture to propose, of rather obscure descriptions did not
occur to myself until after 1 had formed a new theory of my own, the result of a very careful
examination of the ovary in all its stages from the earliest, up to the period of impregnation. At
these early stages when the whole flower has not yet attained half an inch in length probably a
fortnight or more before expansion I invariably find two rows of carpels, one inferior, of 4 or 5
and one superior of 5-6 or more. In the lower series the placentas are ranged round the axis
with their base in the centre and the apex, which is free, towards the circumference. In the
upper the attachment, or base of the placentas, is in the circumference and the apex, also at
first free, directed towards the centre. Between the two rows a diaphragm is always interposed.
The apex of the upper placentas is occasionally, afterwards, prolonged and contracts adhesions
to the axis. , < .
In the accompanying figures 1 have attempted to represent these views. As the fruit
advances in size considerable derangement of this structure progressively occurs which is apt
to mask and confuse the appearances now described.
Having previously ascertained the occasional existence of inversion in the position of
carpels, my first idea was that such an inversion took place in the upper row. This view,
which, equally with the preceding, accounts for the crossing of the placentas I feel inclined
to adhere to, though I confess not without some hesitation, because it implies a complexity of
arrangement rarely met with in the inimitably simple and beautiful operations of nature, but
I think it as difficult to imagine the nearly equally complex and inconceivable operation of the
folding in of one set of carpels over the other, which the explanation of Drs. Lindley and Arnott
demand, while my explanation has the advantage of at the same time accounting for the
double chamber which the ovary presents from its earliest stages, and renders unnecessary the
doctrine of an adventitious verticel of carpels which for the present is mere assumption.
With these explanations I leave the question of structure to consider the one pending on
its determination, viz. whether or not Granteae ought to be preserved as a distinct order or be
reunited to Myrtaceae'1. - , .
On this point so far as the unvarying evidence derived from cultivated plants is entitled to
carry weight on a disputed point—and which I presume it must do until we find that evidenco
invalidated by the examination of others - growing in a truly wild state—we must unquestionably,
I conceive, adopt the views of those who urge the separation, because, the complex structure,
above described, being constant here and unknown among true Myrtaceae, we have
no right, in the total absence of direct confirmatory evidence, to assume that a part is adventitious,
merely because it is at variance with our ideas of what should be, especially while we
have in addition, differences in habit, in the formation of the seed (the cotyledons are foliace-
ous and spirally convolute) and in their pulpy envelope still further to confirm the correctness
of these views.
In coming to this conclusion I do so mainly on the evidence I have myself adduced, attaching
no value to the opinion of Mr. Don, which, being founded, according to his own
showing, on most erroneous views of the structure of the fruit does not merit much consideration.
To the views of DeCandolle more importance must necessarily be attached, as the
reasons he assigns are more satisfactory, though I do not think he has awarded sufficient value
to the very peculiar “ economy of the fruit” while he has laid too much stress on others of much
less note, such as the want of pellucid dots, the absence of the marginal nerve of the leaves and
the pulpy covering of the seed ; thereby, throwing into the shade the true essential character
of the order, which unquestionably is the double row of carpels, with the upper placentas
parietal and crossing the lower axillary ones, which, if I have rightly accounted for, constitute
this a truly curious and unique fruit.
A f f in it ie s . According to the explanation now given, the affinities .of this order remain
to be determined, no known order presenting a similar combination of structure. But adopting
the arrangement of Jussieu and DeCandolle, the one followed with some slight modifications in
this work, we can scarcely find a more appropriate station for it than the one it now occupies,
though but remotely allied to the orders among which it is placed.