438 QUEENSLAND AGRICULTURAL JOURNAL. [1 Dec., 1898. 
Popular Botany. 
OUR BOTANIC GARDENS. 
No. 8. 
By PHILIP MAC MAHON, Curator. 
You pass into the shade-garden by ascending a short flight of steps, and in 
doing so you pass under a shade tree of more than usual beauty. 
It is Albizzia odoratissima, and, as its name implies, is most deliciously 
scented. Its lovely yellowish-white flowers, on a background of the freshest 
and loveliest green, hang to the very ground in a perfect cascade of beauty. It 
is an ideal tree to plant for shade, but, unfortunately, with us it does not bear 
many fertile seeds. There is another species, 4. procera, which is a quick- 
growing and effective shade tree. One thing, if you watch Nature from day 
to day in our Gardens, which will strike you about these trees is the rapidity 
with which they renew their leaves. You have hardly time to notice that the 
branches have become denuded of the hard dry leaves of last year’s growth, 
which have outlived their usefulness, than there is a magnificent crown of fresh 
green foliage with a wealth of beautiful blossoms which scent the air fora 
good many yards around, You enter the shade-garden through a door made 
in imitation of a portcullis of the feudal days, when every man was a law unto 
himself (that is, if he happened to have a castle), and when the power to shut 
out an enemy at a moment’s notice was a matter of some consequence. 
The first thing which will probably strike you about this shade-garden is 
that it seems to be hardly shaded at all, and that the plants seem in some 
unaccountable way to be condoning for this neglect by thriving in a most 
remarkable manner. The fact is that nearly all the shade-gardens one meets 
with are rendered useless by being shaded to a wholly unnatural degree. 
Sunlight is the life of plants. 
At the village of Newtown Park, near Dublin, there stands an obelisk 
100 feet high, and the writer remembers that when he was a small boy 
the following curious circumstance took place concerning it:—T'o one side 
of this obelisk was sown a crop of oats, and when that crop grew up 
it was noted by the villagers, or some of them, with superstitious dismay, 
that the outline of the obelisk was clearly traced in the crop; the oats, 
for an area exactly corresponding to the shape of the obelisk, being stunted, 
while the crop around was quite vigorous. Many were the reasons assigned. 
to account for this fact, spiritual agency being first favourite. But someone, 
pursuing his investigations in the early morning, found that the shadow of the 
obelisk at sunrise was thrown on that identical patch, and deprived it of the 
early morning sun, hence its comparatively poor growth. You remember the 
oft-quoted example of the potatoes in the cellar pushing forward their growths 
towards the keyhole till at last one actually protruded. ‘here is nothing 
overdrawn about this. Plants must have light or perish. Even nut-grass, that 
plague of the gardener, is one of the first to succumb to wantof sunlight. What 
the class of plants usually grown in a shade-garden requires is broken sunlight. 
The vast majority of plants possess most remarkable contrivances and adapta- 
tions of structure to enable them to adapt themselves to the ever-varying 
quantity of sunshine from day to day and at different periods of the same day, 
You have seen and admired the governor-valve on a steam-engine. You 
know that the faster the shaft revolves the wider apart the weights on the 
governor are flung, and the further the lever which closes the steam-valve is 
forced, thus equalising the speed. Soin many a plant when the sun shines 
too full upon the face of a leaf, the plant solves the difficulty by just turning 
the edge to Master Sol until his rays have become sufficiently mild to be borne 
without too great a loss of moisture. That is one of the reasons why the 
Eucalypti (gum-trees) yield so little shade. Their flat surfaces are not turned 
to the sun, Again, if there is an absence of rain the blades of grass will curl 
