84 
ORGANOGRAPHY. 
BOOK I. 
It may be liere remarked, that stole has given rise to the 
name stool^ which is applied to the parent plant from which 
young individuals are propagated by the process of layering^ as 
it is technically called by gardeners. The branch laid down 
was termed propago by the older botanists, and the layer was 
called malleolus, which literally signifies a hammer ; the name 
being thus applied, because, when the layer is separated from 
its parent, its lower end resembles a hammer head, of which 
the new plant represents the handle. 
The Offset, fig. 31. (propagulum, Link), is a short lateral 
branch in some herbaceous plants, terminated by a cluster of 
leaves, and capable of taking root when separated from the 
mother plant, as in Sempervivum. It differs very little from 
the runner. 
The Rootstock, fig. *29. (rhizoma), is a prostrate thickened 
rooting stem, which yearly produces young branches or plants. 
It is chieffy found in Iridaceae and epiphytous Orchidaceae, 
and is often called caudex repens. The old botanists called it 
cervix, — a name now forgotten. 
The Vine, fig. 3*2. {viticula, Fuchs.), is a stem which trails 
along the ground without rooting, or entangles itself with 
other plants, to which it adheres by means of its tendrils, as 
the Cucumber and the Vine. This term is now rarely em- 
ployed. De Candolle refers it to the runner or sarmentum ; 
but it is essentially distinct from that form of stem, because 
it does not root. 
The Pseudohulh is an enlarged aerial stem, resembling a 
tuber, from which it scarcely differs, except in its being formed 
above ground, in having an epidermis that is often extremely 
hard, and in retaining upon its surface the scars of leaves 
which it once bore. This is only known in Orchidaceous 
plants, in which it is very common. 
The term stem [caulis) is generally applied to the ascending 
caudex of herbaceous plants or shrubs, and not to trees, in 
which the word trunk is employed to indicate their main stem ; 
sometimes, however, this is called caulis arhoreus. From the 
caulis, Linnaeus, following the older botanists, distinguished 
the culmus or straw, which is the stem of Grasses ; and De 
Candolle has further adopted the name Calamus for all fis- 
