336 THE BRITISH NATURE BOOK 



BIPINNATE leaves are pinnate leaves the divisions of which are pinnate 

 also (see illustration). 



TRIPINNATE means " three times pinnate." 



TERNATE applies to leaves consisting of three leaflets starting from the 

 same point on a common stalk for example, the Trefoils. 



GLAUCOUS refers to the blue-grey waxy bloom with which certain leaves 

 are covered for example, the Sea Holly. 



About the Flower. If we dissect a simple flower, such as the buttercup, 

 we find it built up of four different organs. First, a whorl or circle of greenish 

 scales SEPALS which, counted together, make up the CALYX (cup), a name 

 suggestive of its purpose namely, of containing or supporting the rest of 

 the flower. Then comes a second whorl or circle of PETALS, usually large and 

 brightly coloured. These together form the COROLLA, or crown. 



Inside the corolla is a large number of STAMENS, little stalks, on the end 

 of each being an ANTHER, or head, from which the pollen is produced. Finally, 

 in the centre is the PISTIL, which usually consists of three parts. The lower 

 part is known as the OVARY, containing minute " eggs " or OVULES, which after 

 fertilization become seeds. Upon the top of the ovary is one or more slender 

 stalks called the STYLE, the tip of which in some cases becomes flattened or 

 rounded. This latter is the STIGMA. Its function is to receive on its sticky 

 surface the ripened pollen grains from the anthers. In some cases (for example, 

 the poppy) the stigma is set directly upon the ovary, without the intervention 

 of a style. The pollen grains germinate by pushing a slender tube down the 

 style into the ovary, where they reach the " ovules " ; and these change into 

 seed, the ovary becoming the SEED VESSEL. The style, stigma, and ovary 

 together form the CARPEL or CARPELS. 



The calyx and corolla together are called the PERIANTH. 



Some flowers have no pistil or ovary, others no stamens ; while some have 

 no sepals, others no petals, and a few neither sepals nor petals. In addition, 

 it should be noted that simple flowers are of different shapes and structures. 



Many flowers for example, the Primrose have their petals so joined as 

 to form a corolla in one piece " MONOPETALOUS." In such cases it is some- 

 times possible to count the number of petals composing the corolla ; in the Prim- 

 rose it is five, but in many other species the shape of the corolla prevents any 

 separation into distinct petals. 



Certain flowers are " lipped " for example, White Dead-nettle and Snap- 

 dragon. 



Flowers may occur singly, on stalks, or in the AXILS (" Armpits ") of the 

 leaves that is, in the angle between the leaf and the stem ; but more often 

 they are grouped in characteristic " INFLORESCENCES." An UMBEL is a 

 flat flower-cluster, in which several flower-stalks (PEDICELS) appear to start 

 from the same point on the main stalk, so that the flowers all occupy one level, 

 forming a flat or convex group (for example, Hemlock). In a SIMPLE UMBEL 

 each flower-stalk carries a single flower ; in a COMPOUND UMBEL each branch 



