Cultural First Principles. 747 



filament together form a stamen, and, as they are the male organs of 

 the flower, all the stamens together are termed the andrccclum. Though 

 it is not so apparent, monstrosities and other evidences prove each 

 stamen to be a modified leaf. The anthers vary in colour and in the 

 way they open to discbarge the pollen, and this latter is also different 

 in different species in colour, size, and form, as is seen under the 

 microscope. 



In the centre of he flower of the buttercup are a number of green 

 ovoid organs collected fn ahead. These qxq CdWeA. carpels ; collectively, 

 i\\Q i:)istil. Each carpel here contains one ovule or immature seed. In 

 the water-lily we have numerous carpels united in a capsule, and each 

 containing many ovules. In the foxglove w^e have two, and in the 

 tulip three united carpels, each containing many ovules. In these two 

 last-mentioned types the pistil is prolonged into an erect pillar-like 

 tube, which is called a style, and is surmounted by a sticky knob called 

 the stigma. This sticky surface is present at the apex of each little 

 carpel in the buttercup, and on the top of the capsule of the water-lily. 

 The lower, hollow part of the pistil, containing the young seed or 

 ovule, is called the ovary. In the pea we have an ovary of one carpel 

 with several seeds, which afterwards becomes the pod, and in the old- 

 fashioned bladder senna {Coluted) we can see still more plainly tliat a 

 carpel — like a petal or a stamen — is only a modifled leaf. 



Each pollen-grain has two coats, of which the outer is generally per- 

 forated in some way. When carried by wind or insects, it falls on the 

 sticky stigma, by the physical process once before alluded to, known 

 as osmose ; the inner coat is protruded, like the finger of a glove, through 

 the perforations of the outer, and grows down the tube of the style into 

 the cavity of the ovary, and into a little opening at the top of an ovule, 

 to be described hereafter. This is fertilization. Thus the pistil is the 

 female, as the stamen is the male organ, and, from the importance of 

 their function, they are termed the essential organs of the flower. Such 

 being the typical structure of the flower, let us trace its relation to that 

 of some of our forest trees. 



In the lime (Tilia) both calyx and corolla are green, as also in the 

 spindle tree (E^ionyrnus Europccus), buckthorn (Rhamnus), maple (Acer 

 camjjestre), and sycamore (Acer pseudo-i^latanus). In the elm (Ulmus), 

 we have little clusters of flowers, with a green calyx and no corolla. 

 In the birch (Bctula alba), the aldei- (Alnus glutinosa), the plane 

 (Platanus), the box (Buxus), the walnut (Juglans regia), the oak 

 (Quercus), the chestnut (Castanea), the beech (Fagus sylvatiea), the. 

 hazel (Corylus avellana), and the hornbeam (Carjnnus hetulus), some 

 flowers have stamens and no ovary, others ovary and no stamens, both 

 kinds occurring on the same tree. Such plants are termed monoiciously 

 diclinous. The willow (Salix) and poplar (Popidus)^ have the male 



