26 THE AUSTRALIAN NATURALIST. 
about 40 species, and over 20 species occur about flour mills, 
ballast is responsible for 19 species, railways and navigation for 
18 species, and about 31 hybrids have been produced in the 
area,” so that it would appear that wool-scouring areas are the 
greatest nurseries of weeds. In view of the above mentioned 
particulars it would be of special interest to conduct similar en- 
quiries concerning the number of weeds or other plants con- 
veyed from various localities by means of fleeces of wool to 
wool-scouring factories in Liverpool and Waterloo in this State. 
In our agricultural and .pastoral districts we find quite a 
different type of weed, such as, for example, the “Noogoora 
Burr” (Xanthium strumarium), “Bathurst-Burr’ (X. spinosum), 
“Star Thistle” (Centaurea calcitrapa), “Black Thistle’ (Car- 
duus lanceolatis or Cnicus lanceolatis), “Cockspur” or “Yellow- 
star Thistle’ (Centaurea salstitialis), “Saffron or “False Star 
Thistle” (entrophyllum lanatum), and the “Black-berry Pest” 
(Rubus fruticosus or R. discolor). These are a few of the very 
worst kind that the farmer or pastoralist has to deal with. In 
our market gardens, as well as our home-gardens, the “Nut- 
grass” (Cyperus rotundus) and “Onion Weeds” (Rowmelia 
rosea) and others are regarded as very bad weeds. The “Prickly 
Pear” (Opuntia spp.) and “St. John’s Wort” (Hypericum per- 
foratum) “Cats-Heads” (Hmex australis) and “Field Bird-weed” 
(Convolvulus arvensis) are also serious pests in many parts of 
the Commonwealth. 
In tropical or subtropical districts quite a different type 
of weed pest may be found, such as, for example, “Lantana” 
(Lantana camara) “Sensitive Plant” (Mimosa pudica) “Coffee 
senna” (Cassia occidentalis) and “West Indian Lead Tree” 
(Leucaena glauca). ‘he latter is a plant of a shrubby habit-— 
or, occasionally it grows into a small tree, producing round- 
headed creamy flowers and pods with an abundance of seeds 
used occasionally by the natives in the islands for necklaces, 
and has spread very rapidly in many parts of the tropies. It 
is particularly .common everywhere in Fiji, following every 
track, road or tramway, or wherever a homestead has been 
established. Although it is generally regarded as a menace in 
Fiji, it is regarded as a useful plant in other parts of the 
tropics, and it is said to be useful for mothering young coffee 
and cocoa plants in newly planted plantations. It is also said 
to be useful as a mulch, and for green-manuring in rubber 
plantation, ete.; and in certain parts it is said to be used suc- 
cessfully (particularly in the Philippines) by forest officers 
