144 
ORGANOGRAPHY. 
BOOK I. 
By Link they have been called Paraphyllia^ and defined as 
“ foliaceous parts, in structure like the leaves, and developed 
before those organs.” 
When they are membranous, and surround the stem like a 
sheath, cohering by their anterior margins, as in Polygonum 
(Jig. 61. «), they have been termed ochrea by Willdenow. Of 
this the fibrous sheath at the base of the leaves of Palms, 
called reticulum by some, may possibly be a modification. 
In pinnated leaves there is often a pair of stipules at the base 
of each leaflet, as well as two at the base of the common petiole : 
stipules, under such circumstances, are called stipels. 
What stipules really are is not well made out. De Can- 
dolle seems, from some expressions in his Organograpliie, to 
suspect their analogy with leaves ; while, in other places in 
the same work, it may be collected that he rather considers 
them special organs. I am clearly of opinion that, notwith- 
standing the difference in their appearance, they are really 
accessory leaves : first, because they are occasionally trans- 
formed, in Rosa bracteata, into pinnated leaves ; secondly, 
because they are often undistinguishable from leaves, of which 
they obviously perform all the functions, as in Lathyrus, 
Lotus, and many other Fabaceas : and, finally, because there 
are cases in which buds develope in their axils, as in Salix, 
a property peculiar to leaves and their modifications. De 
Candolle, in suggesting, after Seringe, that the tendrils of 
Cucurbitaceae are modified stipules, assigns the latter a ten- 
dency to a transformation exclusively confined either to the 
midrib of a leaf, or to a branch; and they cannot be the 
latter. It is, however, more probable that the tendril in this 
order is an accessory bud, a little out of its place, as the 
Bravais’ have suggested. (Ann. Sc., n. s., VIII. 20.) 
It is sometimes difficult to distinguish from true stipules 
certain membranous expansions, or cilias, or glandular ap- 
pendages of the margin of the base of the petiole, such as 
are found in Ranunculaceae, Apocynaceae, Apiaceae, and 
many other plants. In these cases the real nature of the 
parts is only to be collected from analogy, and by comparing 
them with the same part differently modified in neighbouring 
species. 
