362 THE GREEN-HOUSE. [chap. xi. 
Neillii has lilac flowers, and rather an upright 
habit of growth; and V. teucroides is a 
coarse-growing plant, with a long spike of 
white flowers, which turn pink in dying off, 
which has been much more praised than it 
deserves. There is also a yellowish kind, Y. 
sulphurea; V. venosa, a very strong-growing 
species, with purple flowers, and many other 
species, hybrids, and varieties. All the Yer- 
benas require to be grown in sand and peat, 
or heath-mould, and to be kept moderately 
watered: they all strike readily from cuttings 
or layers; and, indeed, when pegged down 
without any slitting or twisting, most of the 
shrubby kinds will throw out roots at every 
joint. When worm casts are observed on the 
surface of the pot, as will very often be the 
case, the plant, with its ball of earth entire, 
may be turned out of the pot, and the worms, 
which will always be found on the outside 
of the ball may be picked off. Worms do 
considerable injury to plants, especially such 
as are in pots, by rupturing the fibres and im¬ 
peding the free percolation of the water, be¬ 
sides giving the surface of the earth in the 
pot, a very unpleasant appearance. The 
