1 6 Making a Bulb Garden 
ing branch or rootstock, somewhat thick- 
ened, growing underneath the ground ; 
(2) a very much thickened rootstock 
with eyes ; or (3) a very much thickened 
bit of underground stem, having no eyes 
but producing roots on its under side, and 
leaves on top. These three forms, be it 
noted, are all solid. True bulbs are not 
solid, but are composed of either a suc- 
cession of thick narrow scales laid one 
upon the other closely, or a succession of 
wider, thinner scales, arranged to enwrap 
each other. The onion is probably the 
most familiar example of the latter kind 
— the enwrapping scale, called the tuni- 
cated bulb, to distinguish it from the nar- 
row, piled up scale or scaly bulb, first men- 
tioned. 
Iris roots are usually rhizomes, al- 
though the English and Spanish varieties 
are tubers; potatoes are tubers, so are 
dahlias ; crocuses and gladioli are corms ; 
lilies are true bulbs of the scaly division, 
while hyacinths are bulbs of the tunicated 
class. 
