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Dehiscence. The mode in which seed-vessels hurst. 
Epidermis. An extremely délicate membrane which coats 
over every part of the plant, except the portion of the pistil 
termed the stigma, and the extremities of the roots termed the 
spongioles. Through the first of these denuded parts, the 
influence of the pollen is conveyed to the ovules, and through 
the latter the water is absorbed which forms the food of the 
plant. 
Exserted. Projecting beyond the surrouuding parts. 
Filament. The stalk to the anther in sonie stamens. See 
Floral Whorls. 
Floral Whorls. The various parts of which the flower is 
composed are generally seated round a centre or axis, in a 
verticillate or whorled manner. These may be referred to 
different kinds, and each kind may be arranged in one or 
more distinct whorls, or at least may be so placed as to succeed 
each other from without inwards in the following order. 
lst. The perianth, which may itself very frequently be 
distinguishèd into two kinds of whorls, the outermost composed 
of sepals, which collectively are termed the calyx ; and the inner- 
most composed of petals, which collectively are termed the 
corolla. In some cases the perianth is entirely wanting, and 
in others it is so little decided in its character, whether it 
should be considered as calyx or corolla, that, to avoid am- 
biguity, the term itself is employed instead of these its sub- 
ordinate parts, and we then say, segments of the perianth, 
instead of using the terms sepals and petals. But when, as 
is more frequently the case, the perianth can be distinguishèd 
into the two parts calyx and corolla, then these possess cer¬ 
tain characters which we shall now explain. 
Calyx. The outer whorl, composed of sepals, which are 
either free or united into a tube ; in the latter case it is termed 
