242 FORMS OF THE FILAMENT. 
without anthers, in which case these structures are termed 
staminodes. These commonly preserve a flattened appearance, 
as in the flowers of the species of Canna. When, as is rarely 
the case, the filament is absent, as in the Cuckoo-pint (fig. 504), 
the anther is described as sessile. 
1. Toe FiramMent.—In its structure the filament consists, 
Ist, of a central usually unbranched bundle of spiral vessels ; 
and 2nd, of parenchymatous tissue which sur- 
rounds the bundle of spiral vessels, and which 
is itself covered by thin epidermal tissue. The 
epidermis occasionally presents stomata and 
hairs ; and these hairs are sometimes coloured, 
as in the Spiderwort and Dark Mullein. The 
structure of the filament is thus seen to be 
strictly analogous to that of the petiole of a 
Fig. 504, Stamen leaf, which presents a similar disposition of its 
aN 5 potckoo- component parts. 
rn ae ue Bt The filament varies in form, length, colour, 
sisting simply of and other particulars; a few of the more im- 
x anc Sista portant modifications of which will be now 
ss 1pon 
the thalamus, alluded to. 
Form.—As its name implies, the filament is 
usually found in the form of a little thread-like or cylindrical 
prolongation which generally tapers in an almost imperceptible 
manner from the base to the apex, when it is described as jili- 
form, as in the Rose; or if it is very slender, as in most Sedges 
and Grasses, it is capillary y (figs. 503 and 505). In the latter case 
the filament, instead of supporting the anther in the erect 
position as it ‘usually does, becomes bent, and the anther is then 
pendulous (figs. 503 and 505). At other times the filament 
becomes enlarged, or it is flattened in various ways. Thus in 
some cases, it is dilated gradually from below upwards lke a 
club, when it is clavate or club-shaped, as in Thalictrum ; or it 
is slightly enlarged at the base, and tapers upwards to a point 
like an awl, as in the Flowering Rush (Butomus wmbellatus) ; 
in other cases it is flattened at the base, the rest of the fila- 
ment assuming its ordinary rounded form, asin Tamaria gallica 
(fig. 506), and species of Campanula (fig. 507) ; or the whole of 
the filament is flattened, and then it frequently assumes the 
appearance of a petal, when it is described as petaloid, as in 
the Water-lily (figs. 453, e, and 522), and in Canna and allied 
plants. 
Sometimes, again, the filament is toothed as in Alliwm (fig. 
508), or forked asin Crambe (fig. 509); or furnished with various 
appendages as in the Borage (fig. 510, a), in which case it is 
said to be appendiculate. 
Length, Colour, and Direction.—The length of the filament 
varies much. Thus, in the Borage (fig. 510, f), and plants 
generally of the order Boraginacez (fig. 511), the filaments are 
Fie. 504. 
