February 2, 1889. 
THE GARDENING WORLD. 
359 
was actually in the good ship Marco Polo in the year 
1861 on her passage home from Melbourne, when she 
ran into an iceberg in the middle of the night, and 
which you can see recorded in the Leisure Hour about 
that date. My other neighbours have been in the 
Fruit and Onion business at the Azores, St. Michael’s, 
Terceria, and Bermudas, and have also cultivated 
their own gardens in New Zealand, but they all seem 
to say they always felt a sort of longing for dear old 
England to lay their bones in. I see they have been 
giving all my Asparagus and Sea Kale beds a dose of 
salted sprat refuse that comes from the sardine factories. 
We yesterday sent you two packages of burnt shell 
dust which I hope will arrive all right. If ever you 
should stroll this way I shall have much pleasure in 
escorting you round the neighbourhood, and as my 
particular old friend, -, chief sketcher for the 
-, says, during his periodical visits to this place 
in summer time, ‘ it is most enjoj'able to take a ramble 
amongst the beautiful gardens of this locality.’ I 
happen to be a member of the Cottage Garden Society 
here, and it often gives the other members pleasure in 
hearing me relate what we see on board ships, both 
flora and fauna. I am sure you would enjoy being 
amongst us.” 
Anthracite. 
I should be glad if some of your readers would kindly 
give me their experience as to the most economical 
way of burning anthracite. I have been told that it 
lasts longer and gives more heat when broken up small, 
but, in my opinion, its lasting power is the greater 
when put on in lumps as large as will go in the 
furnace. I use it in one of Weeks’ upright tubular 
boilers, which has a good draught. — A. Hawkcs, 
Gardener , BisJiopslialt, Hillingdon. 
Davallia Tyermanni. 
Ah important feature of this class of plants is their 
rhizomes, and the variations they present in thickness, 
rambling propensities, and last but not least, the colour 
of the scales with which the most of them are densely 
clothed. In this particular case they are white, or 
nearly so, which gives them a clean and interesting 
appearance. They are about twice the thickness of a 
goose quill, and ramble pretty freely, so that it is more 
suitable for basket culture than for pots. The fronds 
are evergreen, very dark in colour, of moderate size 
and triangular in outline, so that taken altogether it is 
an ornamental and highly useful species, and one that 
should not be omitted from a collection where Ferns 
are grown in any quantity. We noticed it the other 
day doing well at Tower House, Chiswick. 
-o-X<-- 
FORMS OF LEAVES. 
( Continued fromp. 338 ). 
Structure and Venation. 
Upon the direction, nature, and strength of the 
principal nerves depends the form of the leaf and its 
divisions, if there are any ; and in leaves that are 
simply toothed or wholly entire, the direction and 
nature of the venation bear a direct relationship. 
Zoologists talk in a similar strain with regard to 
animal structure, and observe that the bones of the 
head, for instance, assume a certain shape, determined 
by the shape of the brain, the eyes, and the auditory 
organs they have to lodge and protect. The nerves 
and veins constitute the framework and support of 
leaves ; but, unlike bones, they serve as channels for 
the rapid conveyance of water and nutriment to and 
from all parts of the leaf. 
Relative Size of Leaves in reference to their 
Petioles and Internodes. 
Taking the common Lime tree (Tilia vulgaris) in illus¬ 
tration of this, we find the leaves are obliquely heart- 
shaped, a peculiarity common to most species of Lime. 
The explanation is by no means easy, but I would 
suggest the following : The tree has long, spreading, or 
pendent branches, and in order to ensure a proper 
exposure to light, the leaves are all directed to the 
upper side of the branches and arranged more or less 
regularly in one plane. They are usually, in healthy 
trees, so closely placed that one leaf will overlap the 
posterior side of the one next above it, and examination 
proves this to be the smaller half. It would be wasted 
energy were the tree to develop this part without 
ensuring for it a proper exposure to light. Further, 
the leaves being unequal-sided, they offer less resistance 
to a strong wind, and, consequently, during severe 
gales it is an advantage to them to turn on one side 
so as to avoid being damaged or torn to pieces. Tilia 
cordata has much smaller leaves, and in order to utilise 
space and sunlight the internodes are shorter, and a 
greater number are arranged in the same area. A third 
species, also British (Tilia platypliyllos), has much 
larger leaves than either of the foregoing, and conse¬ 
quently fewer in the same area. Another striking 
peculiarity is that the foliage has a venation character¬ 
istic of lohed or palmate leaves, and yet normally 
remains undivided. Instead of running straight to the 
margin and forming lobes, the principal nerves become 
incurved, much branched, and lose themselves within 
the margin. An exotic species from Amurland shows a 
considerable advance on our natives, and has equally 
heart-shaped leaves, with the three principal nerves 
straight, and running out so as to make them distinctly 
three-lobed. 
The Oriental Tlane is a magnificent tree, with large 
palmate leaves, and attains a height of 60 ft. to 80 ft. 
in this country, developing a large spreading head with 
horizontal or drooping branches. It withstands the 
smoke of towns well, and thrives in the very heart of 
London, and ought to be extensively planted wherever 
there is sufficient space to develop its magnificent pro¬ 
portions. The typical form has five long finger-like 
lobes to its leaves, giving them an elegant appearance, 
but this form, as well as a variety with distinctly wedge- 
shaped leaves, namely, P. orientalis cuneata, is inferior 
in point of size and magnificence to the Maple-leaved 
Plane (P. o. acerifolia) ; this latter is the commonest 
form in Britain, and almost exclusively that planted in 
the streets of London. The leaves on healthy young 
specimens attain a handsome size, and having broad 
lobes never present the finger-like appearance of the 
type. The venation is precisely similar in all the forms, 
and has three strong nerves with a strong branch from 
each of the lateral ones ; this gives the five-lobed out¬ 
line of the leaf. They run straight to the tips of the 
lobes, giving the leaves their characteristic palma.te 
appearance, and they, as w T ell as their sub-divisions, 
are well arranged for the rapid conveyance of nourish¬ 
ment to all parts of the leaf. The three primary 
nerves have been inherited from a long line of 
ancestry, and are traceable from the first miniature, 
wedge-shaped leaf of the seedling to those of the 
adult tree. The latter are beautifully arranged in one 
plane, so as to utilise a maximum of the sun’s rays ; 
and the horizontal branches in young trees especially 
are strikingly bent in zigzag manner, so as to assist the 
leaves in taking their positions alternately. Owing to 
the great size of the leaves, the internodes are much 
longer than those of the Lime tree, consequently the 
branches are much fewer, and altogether the tree 
presents a less twiggy appearance after the fall of the 
leaf than the Lime. The Plane is considered by some 
good authorities to he a lineal descendent of the 
Saxifrage family, with a much reduced inflorescence 
and seed vessel. 
The size of leaves and their arrangement may be 
further illustrated by reference to two of the commoner- 
species of Sumach in English gardens, namely, the 
Venetian Sumach (Rhus cotinus), and the Stag’s-horn 
Sumach (Rhus typhina). The former has simple, 
obovate entire leaves, with incurved nerves that fork 
and branch before reaching the margin, which is sur¬ 
rounded by a colourless cartilaginous border. This 
form of venation is very characteristic of undivided 
leaves, and may alw-ays be expected where they are 
wholly entire or merely toothed. The leaves being 
here small are numerously arranged on the branches. 
A very different case is presented by Rhus typhina, 
which has feathery, pinnate, drooping, Fern-like 
leaves that attain a length of 1 ft. to 3 ft. under 
favourable conditions. Owing to their size the leaves 
are arranged umbrella-fashion at the apex of the stem 
and branches. The venation is highly developed, and 
not only are the primary and secondary nerves straight, 
but the tertiary ones run straight into the marginal 
teeth, offering facilities for further division, and this 
actually happens in Rhus glabra, another closely allied 
species. Rhus typhina inherits this tendency to divide 
at a very early age, and the first true leaf of the seed¬ 
ling is deeply three-parted and cut. The leaves of the 
Sweet Chestnut are closely arranged, but being long 
and narrow do not overlap or interfere with one another 
to any extent. The leaves of the common Barberry 
are small, and arranged in clusters on short lateral 
branches. The primary ones on strong-growing shoots 
are reduced to the condition of three-parted spines that 
serve for the purpose of protection, from browsing 
animals for instance. In striking contrast to this may 
be noted the common Mahonia (Berberis aquifolium), 
with truly pinnate leaves whose marginal teeth run out 
into spines like those of the Holly, for the common good 
of the plant. Widely different as both these species of 
Barberry appear, they present the same form of leaf in 
the seedling state. This is roundish or heart-shaped, 
and the Mahonia, after producing four to five of this 
form, develops one with three leaflets, and from thence 
progresses to the adult state. 
The Honey Locust (Gleditschia triacanthos) exhibits 
a remarkable instance of variability in the leaves. 
They are pinnate or bipinnate, not only on the same 
tree but on the same branch, and an individual leaf is 
sometimes pinnate at the base, bipinnate in the middle, 
and again simply pinnate at the apex, while some 
leaflets are half cut up into secondary ones, leaving the 
other half undivided. In all this invariability nature 
shows how she can sport at will, and demonstrates 
unmistakably how a bipinnate leaf can originate from 
a pinnate one. The explanation of this variability, on 
examination of trees of different ages, points to its 
being a mode of adaptation to conditions and sur¬ 
roundings. The large bipinnate leaves are most 
abundant on young, fast-growing trees, and on 
vigorous branches, while the pinnate leaves generally 
clothe the bases of the branches where the internodes 
are short, or form rosettes on the short snaggy spurs of 
old trees or branches. The simply pinnate leaf is a 
convenient reversion to a more primitive condition, as 
the bipinnate form is more liable to damage from 
exposure to winds, and if produced on the short snaggy 
branches would shade one another to a damaging 
extent. Gleditschias have existed since the Pleiocene 
Flora of the Tertiary system lived. 
-->X<—- 
INSECT-CATGHING PLANTS. 
At the annual meeting of the Manchester Field 
Naturalists and Archaeologists Society, held last week, 
Mr. Leo H. Grindon delivered an address on this 
interesting subject, from which we take the following 
extracts :—The first notice in books of insect capture 
by plants is in old Gerard, A. D. 1597. Describing that 
pretty garden annual, the Silene Armeria, he says, ‘ If 
flies do light upon this plant they will be so entangled 
with the limyness [of the stalks] that they cannot flie 
away ; insomuch that in some hot day or other you 
shall see manie flies caught by that meanes, whereupon 
I have called it catch-flie or lime-woort.” (Herbal, p. 
482.) In conformity with botanical usage, all the 
other species of Silene are now called Catehfly in the 
vernacular, whether or not agreeing with S. Armeria 
in respect of properties. Silene, it may be remarked, 
points in a way too obvious to need mention, to the 
self-befouled old drunkard of classical mythology. Of 
similar examples of capture by means of simple sticki¬ 
ness of surface it is easy to find plenty. They occur 
among the Capa Ericas, the corollas of which often 
present crowds of unfortunate little wretches glued fast 
to the outside, and in a way that cannot be of the 
slightest use to the plant, merely annoying the 
gardener. In the open air we find similar havoc made 
among the midges and their kindred by the common 
yellow Azalea, and yet more conspicuously by some of 
the American species of that favoured genus. No 
plants, even among those provided with special appa¬ 
ratus for slaying, are more cruel or more greedy than 
these sticky-flowered Azaleas. The corollas abound 
with viscid hairs, once setting foot among which there 
is no release. In the present instance, the poor 
innocents appear to be lured to their doom by the 
odour of the flower—assuming, that is, that the olfac¬ 
tory powers of insects correspond with our own, the 
odour in that case being analogous in its deadly 
invitation to that of the toasted cheese in the mouse 
trap. But too much must not be made of the supposed 
seductive power of flower scent, for the Ericas present 
no such bait, being altogether devoid of perfume ; they 
lure and kill notwithstanding. Struggling to escape 
simply makes matters worse, the captive then becoming 
another Gulliver among the Lilliputians. Several of 
the Saxifrages capture in the same way, by means of 
sticky peduncles and calyces. So do several of the 
Rubi, Rubusodoratus, andR. phcenicolasiusin particular. 
So do most of the plants which have for their specific 
appellation, “viscosus.” 
This will suffice for the destroyers which can hardly be 
supposed to profit by their work. I do not deny that 
they profit by it. He is a bold man who denies even 
the simplest proposition until possessed of good evidence 
of its falsity, so that in days to come it may be discovered 
perhaps that some good use is really and truly sub¬ 
served. For the present, however, that anything comes 
of such captures is eminently doubtful. 
The illustrations of special mechanism having insect- 
capture as the result, are various, and met with in quite 
