234 DEVELOPMENT OF 
The origin and function of these organs, although in all ; 
cases referable to the leaf, as a type, vary à good deal. 
'The ochrea is quite distinct, and is a mere dilatation of the 
petiole; the margins of the dilated part cohering and forming 
a sheath. 
Such are all dilatations of the petiole, which may be carried 
so far as to produce vaginoe. Ex. Nandina, Aralia, and pro- 
bably all Polygonez, Rosa? 
2. Stipules may be independent organs, analogous in all 
-respects to the scales of buds as in Dipterocarpez, Ficus, in 
which last they are indifferently, simple, or double. 
3. They may be referred to the pinnules of leaves, of which 
they form necessarily the lowest pair: this view is borne out 
by their development. And this is probably the case with all 
independent bistipulate plants with alternate leaves. 
` Ex. Passiflora, Bucklandia? Hymenea. 
It is probable perhaps, that in some as Pouzolzia pentandra, 
they have two origins, in that they represent pinnules of the 
leaves, and also independent organs, as this plant presents 
entire interpetiolar stipulae above ? And the usual form below. 
Stipulie do not exist in Stellate, as is shewn, I think, by 
Rubia cordifolia, in which all the leaves of the verticel are 
stalked, and which do not exceed four in number. This last 
however only proves that they cannot be stipulz, as generally 
understood, since the number then ought to be six ; but they 
may be independent leaves, as in many Rubiacez, although I 
know no instance in which they are distinctly stalked. 
The study of Bucklandia first led me to adopt the idea of 
their true nature, which is, that they are modifications of 
leaves, and that in all cases they are analogous to the scales of 
buds: and that hence they have nothing to do with the 
leaves to which they are supposed to belong. 
This is most distinct in those species which have entire con- 
lute stipulz, as Ficus and Dipt pus, in which the attach- 
ment takes place all round the axis and above that of the 
petiole. Hence this view of the case does away with the un- 
natural idea of alternate leaves and opposite stipules due to. 
cohesion, Thus Bucklandia becomes no longer singular on 

