THE AUSTRALIAN GARDENER. 
ae Tie) 
15 es 
OcToBER 1, 1903. 
spike-like racemes, 4 to 8 in. long. Highly 
recommended as a garden shrub. 
~GREVILLEA JUNIPERINA. is a very 
dense, compact grower, and in appearance 
very much resembles some of the European 
Junipers.~ A very nice specimen of this 
species can be seen in the’ Adelaide Botanic 
Gardens. 
HOW PLANTS CLIMB. 
——-— 0 — — — 
Some plants climb simply by threading 
their way through their supports, the 
spreading growths that they afterwards 
make preventing them from slipping back. 
Zi the climbing Rose this is helped by the 
recuryed prickles. In this connection 
the Elaeagnus deserves attention. At 
first the side shoots point upwards, then 
higher up they are at right angles with 
the stem, after that they point downwards 
so as to form a hook, which catches over 
any convenient support. But the curious 
thing to note is,that in these hooks the 
inner angle is filled in to give the neces- 
sary strength, for it is well known to 
mechanicians that without such filling in 
tie angle is extremely weak. 
A. second mode of climbing is by twin- 
ing round the support when this is suffi- 
ciently fine. Each plant has a definite 
direction of twist, described as right- 
handed or left-handed, positive or negative, 
counter-clockwise or clockwise. The two 
first are ambiguous, the third is clumsy. 
Looking at a compass and starting from 
east, the two possible directions are to- 
wards the north or towards the south. 
Les us call the first EN-rotation, the se- 
cond ES-rotation. The Hop, then, EN- 
rotates; the Scarlet Runner ES-rotates. 
The Hop is furnished with small anvil- 
shaped hairs which assist its grip; these 
ace just visible without a lens. Another 
favorite method of climbing is by 
Tendrils; the advantage is that. the stem 
Gan now grow straight up instead of hay- 
ing to lose time in twining, and the con- 
traction of the tendril, after it has taken 
hold, helps to draw up the stem. Tendrils 
have different sources; in vines they are 
modified flower stalks, in Lathyrus-an ex- 
tension of the mid-rib of the leaf, and in 
Sarsaparilla they are readily seen to be 
_ altered stipules. The tendril of Bignonia 
Venusla ends in three sharp claws. The 
leat-stalk of Lophospermum acts as a ten- 
dril by clasping the support. Some plants 
grcwing against a wall put out adhesive 
discs, as in the Virginian Creeper; and 
others aerial roots, as in the Ivy and 
Climbing Fig. When thd Ivy gets beyond 
its support it flowers, and the leaves 
change from lobed-leaves to heart-shaped. 
The free tendril of a plant sweeps slowly 
round as if in search of a support, but for 
full information on this subject the reader 
is referred to Darwin’s book, as no sum- 
mary can do justice to his minute and care- 
fully-conducted experiments, 
> REVIEWS. + 
——_90——_- 
‘KERNER’S “NATURAL HISTORY OF 
PLANTS,” WITH BOTANICAL NOTES 
iene Wig? 
[We shall be pleased to review any books, mag- 
azines, or periodicals dealing with plants sent to 
us for that purpose.—Ep. |. 
To prevent rain and dew stopping up 
these stomata many contrivances are 
found. Some leaves are furnished with a 
waxy coating which sheds the water: 
the upper surface of a cabbage leaf 
1s a. case in point. Others have 
a hairy or felted surface; others 
have little projections on the leaf 
surface, drops of dew rest on these, and 
bridge over the hollows where the stomata 
aco placed, these, therefore, remain dry. 
_ Some leaves are rolled back so as to keep 
the water away from the stomata; others 
have ridges or embankments for the same 
purpose. That these contrivances do keep 
off the water is easily proved by immersing 
a leaf and noticing how dry that side of 
the leaf remains where the stomata are 
situated. 
But whilst transpiration needs to be 
encouraged in the wet season, in the dry 
season excessive transpiration must be 
checked. This is mainly done by the 
guard-cells of the stomata: when the air 
is dry the inner concave edges of the guard- 
_cells straighten and close the aperture. 
But the waxy secretion on many leaves, 
already referred to, the varnish, the limy 
and other salts and the hairs all help to 
ward off the direct action of the sun’s rays, 
and restrict exhalation. In this connec- 
tion Kerner gives wood-cuts of a number 
of characteristic hairs, woolly, jointed, 
silky, ribbon-like, spiral, star-shaped, um- 
brella-like, T-shaped, shield-shaped, &c., 
&c., and I would recommend any who has 
a low-power miscrscope or even a good sin- 
gle lens, to make a collection of leaves for 
the purpose of showing the yery great 
variety of leaf-hairs. 
Another method for the plant to avoid 
the extreme heat of the sun is to arrange 
its leaves north and south, so that the 
edges are presented to the noon-day sua. | 
The Compass plant (Sylphium) does this, 
so that if you look at a number of plants 
in the N. and 8. direction they appear as if 
flattened out artifically. One of the wild 
lettuces shows the same peculiarity. 
Other plants, including various grasses, 
fold their leaves together as protection 
from the noon-day sun, or even to avoid 
sudden. bursts of sunshine. Bee at 
Still on the subject of leaves, Kerner 
next describes the various manners in 
which the young leaves are folded in the 
bud, and then proceeds to the fall of the 
leaf, showing that leaves do not fall mereiy 
because they are dead, but are thrown of 
by the formation of a “separation layer” 
at the base of the foot-stalk. : 
Then comes “Phyllotaxis,’ or the a:- 
rangement of leaves on the stem, generaliy 
in a spiral. 4f you pinch the tips o:t 
two leaves standing one above the other 
you wul find that there is a definite i Uui- 
ber of leaves included in the set. UE 
course, only one of the marked leaves 1s 
counted in. ‘These sets are one of the 
following series, 1, 2, 3, 5, 8, 13, &c., where 
each new number is the sum of the two 
previous ones. _ And to complete the set 
you have to go round the stem as many 
times as the first of these two previous 
numbers. 
hus, if there are five in a set you have 
to go round twice, if eight three times. 
bive 1s common, and eight not infre- 
quent, but for the higher number tir cones 
are most suitable. 
Another interesting chapter is upon 
“Leaf Mosaics ;” that is, the way in which 
leaves fit into one another when looked 
down upon. Of course, this fitting in is 
designea to give every leaf a fair share of 
lignt, and it is really marvellous to see. 
how beautifully some leaves dovetail to- 
gether, . 
Begonias, Campanulas, Climbing Fig, 
Nightshade, Elm, and Ivy may be taken 
as striking examples. 
We have seen now plants protect them- 
selves from heat and moisture, but how 
are they to keep off browsing animals. 
_ Hirst, by poisons, as in tne case of the 
Deadly Nightshade; next by offensive 
odors, as in the Datura, common in the 
Torrens bed; thirdly by unpleasant tastes. 
Then, again, water forms an excellent 
protection against grazing animals, who 
Seem to avoid plants covered with dew or 
raindrops. A Lady’s Mantle (Alchemilla), 
which is thus avoided, is eagerly taken as 
food when the water is shaken off. 
But the chief protection against animals 
is furnished by spines and prickles, and 
these are frequently undeveloped above the 
line to which ruminants can reach. For 
examples, see the Wild Pear and the 
Holly. In many cases the leaves them- 
selves are prickly, as in Thistles and Acan- 
thus, Aloes and Agaves. Other leaves 
have saw-like edges; others, like Solanums, 
have prickles projecting above and below 
from the blade of the leaf. Some, too, 
like Nettles, have stinging hairs, which 
break off and leave their points in the 
flesh. 
The Cactus-like plants have particularly 
unpleasant spines, and it may be found by 
experience that they penetrate the skin 
before the hand is thought tol be near 
them. This arises from the extreme 
point being black, and, therefore, invisible. 
It is worth while comparing the points of 
some of these spines with that of a needle 
under the microscope. It will be seen, 
too, that such spines are often barbed. 
Licur Emirrep sy Prants.—It is well 
known that certain mushrooms emit 
enough light to read by, and I am desirous 
of trying whether they would affect a pho- 
