76 
THE PERIANTH 
sporophylls (probably stamens) which gave up their spore- 
producing function, and in consequence probably became 
larger by the diversion of the food materials formerly given 
to the spores ; or again, it is possible that both these views 
have some truth in them. However it may be, it is 
probable that the perianth first appeared as a few greenish 
or brownish coloured leaves at the base of the flower, and, 
by covering the stamens and carpels in the bud, performed 
for them the important function of protection from the 
weather. True simple perianths of this type occur in some 
of the lower cohorts both of Monocotyledons and Dicotyle- 
dons. We have again to be on our guard against cases in 
which abortion of part of a double perianth has occurred, 
i.e. against true apetalous flowers. 
With the advance of insect-pollination, specialisation is 
shown in the perianth, and in most flowers now existing 
there is an outer series or whorl of greenish or brownish 
protective sepals forming a calyx , and an inner series or 
whorl of more or less brightly coloured petals forming a 
corolla , which aids in the attraction of insects. Most 
probably this inner series of leaves has been derived from 
the stamens ; when the latter lose their sporophyll function, 
as in double flowers, they readily become transformed into 
petals. Transition forms occur in Nymphaea ; and are 
sometimes quoted as proofs of the origin of stamens from 
petals ; the argument is equally good if reversed, and it is 
also a priori far more probable in this form, as a moment’s 
consideration of the intermediate forms will show. 
Concrescence is frequent in the perianth, e.g. in Sym- 
petalae, and between perianth and stamens. Irregularity is 
also common. 
Descriptive Terms , &c. Flower with perianth, chlamydeous , 
without, naked or achlamydeons ; with one whorl of perianth, haplo - 
or mono-chlamydeous or ‘ incomplete 1 ( apetalous if the phenomenon is 
due to suppression of corolla), with two whorls, di - or diplo-chla??iydeous 
or 4 complete l Perianth with leaves of one kind only (tepals) homo - 
chlamydeous, of two kinds ( sepals forming a calyx , and petals a corolla ), 
heterochlamydeous. 
The perianth (calyx, corolla) may be hypo-, peri-, or epi-gynous ; of 
free organs (poly-phyllous, - sepalous , -petalous) or concrescent (gamo- 
phyllous , - sepalous , gatno- or sym-petalous) ; in the latter case the con- 
crescent part or tube bears the free lobes, teeth , or segments together 
forming the limb . It may also be regular (actinom orphic) or irregular 
