INTRODUCTION 
is, however, less common in the calyx than in the corolla ; hut a frequent 
form in specialised, insect-pollinated, horizontal flowers is the bi-labiate or 
two-lipped, in which five sepals, united into a tube below, are divided by 
deep notches or sinuses into two groups of two and three respectively. In 
Gorse and Broom, for instance, two sepals form the posterior or upper lip and 
three the anterior or lower, though the sinuses between each sepal are often 
indistinct. In the Sage and Mint Family, which are known technically as 
Labiatce {i.e. lipped), there are, however, three sepals in the posterior and 
two in the anterior lip. Polysymmetric gamosepalous forms of calyx include 
the tubular , as in Centaury ; the tubular and plaited , i.e. folded so as to he 
star-shaped if cut across, as in the Primrose ; the wider cylindric , as in the 
Cheddar Pink ; the bell shaped or campanulate, as in Henbane ; and the 
barrel-shaped or urceolate , as in the Sea-Campion. In this latter and some 
other cases the calyx is termed inflated, because there is a space between it 
and the corolla, an adaptation apparently to prevent the illicit stealing of the 
honey in the corolla-tube by insects boring through the wall of the calyx- 
tube. In some of the Family Composites , and in some other flowers, the 
upper free portion or limb of a gamosepalous calyx is replaced by a circlet 
of hairs known as a pappus, which develop chiefly in the fruit stage. In 
the Dandelion this pappus is stipitate or stalked, being carried up on a 
slender calyx-tube, while in the Thistles it is sessile. The hairs of the 
pappus of the Dandelion are unbranched or pilose ; those of the Thistles are 
feathery or plumose. In duration the sepals may be caducous, falling old' as 
the flower opens, as in Poppies ; deciduous, falling with the petals and 
stamens after fertilisation, as in the Cherry or Plum ; ox persistent, remaining 
in the fruit stage, as in the Strawberry. When persistent, they are often 
marcescent or withered, as in the Apple and the Gooseberry. 
Whilst the calyx is commonly green, often hairy externally, as a 
protection against small crawling insects that might steal the honey 
without effecting cross-pollination, and generally protective 
Corolla . c . u 6 ,, . c r y - 
in function, the corolla is more often delicate in texture, 
brightly and conspicuously coloured and scented, serving the special 
purpose of attracting flying insects. Its petals are commonly attached by 
a narrow base, sometimes drawn out into a long narrow portion, known as 
the claw, as in Wallflower or Campion ; and they are generally rounded, 
XXXV 
