86 THE FLOWER. 
Hop (Humulus). When hermaphrodite, male, and female — 
flowers are found irregularly set on the same plant, or on — 
different plants, they are called polygamous, as in a species 
of Bed-straw (Galium cruciatum). 
290. The calyx and corolla are envelopes which cover and — 
protect the sexual organs, and probably perform some im- 
portant function connected with air and light: the peduncle — 
gives support to the envelope and the sexual organs, and 
connects them with the stem; and the bractea is an appen- — 
dage which protects the flower in the bud, and in some cases — 
‘supplies the place of the calyx. 2 
291. The flower is considered by modern physiologists as __ 
composed of several whorls of metamorphosed leaves or 
bractee ; the calyx being the lower or external whorl, the — 
corolla the next, the stamens the next, and the pistil the inner _ 
or last whorl. This will be explained more particularly at — 
the end of this chapter. 
292. Plants of this kind are called phenogamic, or flower- 
ing, because they produce flowers : sexual, because they have 
sexual organs, (stamens and pistils)), embryonate, because — 
they possess an embryo or particular form of seed; cotyledo- — 
nous, because the seeds are provided with cotyledons or seed- 
lobes; and vascular, because they contain spiral vessels. 
They receive these names to distinguish them from a class of — 
plants which are destitute of spiral vessels, of cotyledons, of 
an embryo, of sexual organs, and of flowers. 
Il. THE PEDUNCLE. 
293. When the flower is attached to the stem or branch 
by means of a stalk, this organ is called a peduncle ; see 4, 
fig. 12, par. 286. When there is no peduncle, the flower 
___ being attached by its base, it is said to be sessile, as in Com- 
mon Star-thistle (Centaurea ealeitrapa), and in Dodder 
(Cuseuta). 
294. The poten eld a spe whe grows om 
