INTRODUCTION 
landing-place for insect visitors or labellum (Latin, a little lip). Honey- 
suckle is exceptional in having four reflexed posterior petals and a single 
one reflexed as a labellum. Bi-labiate corollas may be either ringent or 
gaping, as in the Dead-nettles and most of the Family Eabiatce ; or 
personate , i.e. mask-like, as in the Snapdragon, in which the two lips are 
closely pressed together, so as to require to be forced apart by the insect. 
Whilst the Snapdragons have a honey-pouch at the base of the corolla- 
tube, the Toad-flaxes have a spur. The ligulate or strap-shaped corolla is 
characteristic of the outer or “ray ” florets of such Composite as the Daisy 
or the Ragwort and of all the florets in the Sub-Family Liguliforce , such 
as the Dandelion. It has five petals, united in a tube below, some of 
which expand as a strap-shaped limb notched at its apex so as to 
suggest the number of petals so developed. 
The colours of the petals are connected with their perfumes and with 
the visits of insects. Petals are supposed to be derived from the degenera- 
tion of stamens ; and to have been, in primitive types of flower, yellow or 
white. Many white flowers are sweet-scented and are pollinated by night- 
flying moths ; whilst bees show a preference for blue flowers, which are 
less common ; and wasps, for orange or dark red or brown flowers. Many 
weeds of world-wide distribution, on the other hand, have small scentless 
white blossoms, are seldom visited by insects, and produce abundance of seed 
as the result of self-pollination. Lines of dots on the petals, as in the Pinks, 
or dark lines, as in the Common Mallow, are “ honey-guides,” directing 
the insect visitors to the particular part of the flower at which nectar is 
secreted. 
In duration, the corolla may be fugacious , falling, that is, directly the 
flower is gathered, as in the Flaxes ; deciduous , falling after pollination, as is 
usually the case ; or persistent , as in Campanula , in which case it remains in 
a shrivelled state round the fruit. 
/Estivation (Latin cestivus , belonging to summer), the folding of the 
floral envelopes in the flower-bud, is often characteristic of Families and 
is described mainly as in the vernation of the leaf-bud. In Clematis the 
sepals are valvate, touching at their edges without overlapping ; whilst in 
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