April, 1928 
The Queensland Naturalist. 
61 
anee. One of the facts known to every Brisbane gardener 
is that some plants will not flourish close to the south- 
side — the shady side — of the house, whereas on other 
sides they grow well. Some on the other hand grow best 
in the shade. Many ferns, Primulas and Begonias, show 
this preference, and there are numerous plants of inter- 
mediate taste. There are two important factors at work 
• — the amount of heat and the amount of light. In 
Queensland we have practically the same duration of 
light on the tablelands as on the nearby lowlands, but 
the increased altitude results in a reduced temperature, 
and temperate plants, both weeds and cultivated 
species, which in Brisbane either fail or grow with diffi- 
culty, thrive on the Darling Downs. The important 
thing here is temperature. The thriving of some plants 
on the shady side of Brisbane houses is due to something 
more than temperature alone, though this is important. 
Many delicate species cannot survive exposure to full 
sunlight. Their leaves, thin and internally constituted 
so as to function efficiently in weak light, are scorched 
and bleached by exposure. Even amongst such sun- 
loving plants as roses there are varieties, such as Hadley, 
which take on an undesirable bluish tint in strong sun- 
light. 
Full exposure to sunlight and heat is required by 
such plants as crotons and acalyphas, which make won- 
derful displays in North Queensland. Where these con- 
ditions obtain all the year round, zinnias, sunflowers, 
and other heat and light-loving annuals, may be grown 
all the year round. In Southern Australia they may be 
grown only in the summer. Many glasshouse plants, 
such as ferns, begonias, and avoids, flourish in hot sur- 
roundings, but avoid intense sunlight. Under glass 
tomatoes, grapes, bananas, and pineapples are grown in 
England. Darwin’s highest praise of the Tahitian pine 
apples was to compare them favourably with those grown 
in England. Here is a ease where heat is important, light 
being subsidiary only. 
A few observations on cultivated plants in Brisbane 
show the effect of sunlight on the flowering of some 
common species. Candytuft with 11s is in full bloom in 
July. In an oval of plants edging a flower-bed in the 
middle of which grew tall plants, those on the north side 
received the morning and afternoon sun, those on the 
south being shaded most of the day. Those with the 
northern exposure had on an average forty-nine heads oL* 
flowery each, those on the south twenty-three, or less 
