The Flowers

The broad-leaved trees are Angiosperms and produce flowers. Basically a flower possesses a stalk or pedicel terminated by a short receptacle which bears lateral floral organs. From the outside to Hie centre are: The caly*, consisting of several, usually five, sepals which are often green and protect the flower bud. The corolla, usually consisting of five petals. These are often brightly coloured and may be fused together forming a cup-or funnel-shaped sympetalous corolla. The androecium of few to many separate stamens. Each stamen has a thin stalk or filament and a terminal anther which produces the pollen The stamens are sometimes borne on the corolla, i.e. epipetalous. The gynoecium of one or more carpels. Each carpel consists ot a hollow ovary containing one to many ovules, a style and a terminal stigma. In most species the carpels are few and more or less fused together. Pollination is the transfer of pollen from the anthers to the shgma. Brightly coloured flowers, which are often scented and produce nectar, are usually pollinated by

Wind Pollinated Flower

insects. The small green flowers of some trees, e.g. Birch, are wind-pollinated.

Many flowers contain both stamens (male) and carpels (female) and are therefore hermaphrodite (Tulip Tree), In monoecious species (Birch) the male and female flowers are borne in separate groups on the same tree. Species in which the male and female flowers occur on different trees are dioecious (Willows). Flowers are sometimes home singly but more often they are grouped in different types of inflorescences. Diagrams of some of the commoner types are given below.

Catkin Inflorescence Diagram

scorpoid cyflit dichasiĆ¢t cirme

N.B. The catkin it a variant of the spike.

Female Heliothis Virescens
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