CHAP. II. 
HAIRS. 
61 
emit little branches along their whole length : when such 
branches are very short, the hairs are said to be toothed or 
tootkletted, as in the fruit of Torilis Anthriscus ; when they 
are something longer, the hairs are called branched, as in the 
petioles of the gooseberry ; if longer and finer still, the hair 
is pinnate, as in Hieracium Pilosella ; if the branches are 
themselves pinnate, as in Hieracium undulatum, the hairs are 
then said to be plumose. It sometimes happens that little 
branchlets are produced on one side only of a hair, as on the 
leaves of Siegesbeckia orientalis, in which case the hair is 
called one-sided (secundatus) ; very rarely they appear upon 
the articulations of the hair, which in that case is called 
ganglioneous. (Plate I. fig. 9. Verbascum Lychnitis) : the 
poils en goupillon of De Candolle are referable to this form. 
Besides these, there are many other modifications : hairs are 
conical, cylindrical, or moniliform, thickened slightly at the 
articulations {torulose), as in Lamium album, or much en- 
larged at the same point [nodulose), as in the calyx of Achy- 
ranthes lappacea. In Polystachya luteola the hairs of the 
labellum are moniliform, or necklace-shaped, with the articu- 
lations all spheroidal, equal sized, and disarticulating at the 
slightest touch when the flower is expanded, so that the part 
on which they grow seems as if it were covered with fine 
powder. 
Hairs are sometimes said to be fixed by their middle (Plate 
I. fig. 10. c) ; a remarkable structure, common to many 
different genera: as Capsella, Malpighia, Indigofera, &c. 
This expression, however, like many others commonly used 
iu botany, conveys a false idea of the real « structure of such 
hairs. They are in reality formed by an elevation of one 
bladder of the epidermis above the level of the rest, and by 
developement of a simple hair from its two opposite sides. 
Such would be more correctly named divaricating hairs. 
When the central bladder has an unusual size, as in Mal- 
pighia, these hairs are called puils en navette [pili Malpighiacei) 
by De Candolle, and when the central bladder is not very 
apparent, poils en fausse navette (pili pseudo- Malpighiacei, 
biacuminati), as in Indigofera, Astragalus asper, &c. In 
many plants the hairs grow in clusters, as in Malvaceae, and 
