INTRODUCTION 5 



Flowers. 



The male and female flowers of conifers are produced separ- 

 ately either on the same tree or on different trees. The male 

 flowers consist of a number of stamens arranged in catkin-like 

 clusters, each stamen usually including an anther and filament. 

 In colour they are usually some shade of yellow, violet, or deep 

 crimson. The anthers are produced either on the sides or on the 

 undcr-surface of the staminal leaf or sporophyll, which consists of 

 a filament expanding above into a scale-like connective. The 

 pollen grains are globular and sometimes winged. 



The female flowers are borne in cones, each flower usually 

 consisting of a bract and a scale, one above the other, the lower 

 one (the bract) being sterile, the upper one (the scale) fertile 

 and bearing a seed or seeds on its upper surface. The relative 

 proportions of the bract and seed scale vary in different cases 

 so that while in some genera, such as Abies, the bract and scale 

 are always distinguishable, in others the two are so intimately 

 blended as to be indistinguishable to the naked eye when the cones 

 are ripe (see Pinus). The seeds are not, as in other flowering 

 plants, enclosed in an ovary, but lie exposed on the upper surface 

 of the scale ; hence the name " Gymnosperms " or " naked- 

 seeded plants." The flowers are usually wind-pollinated. 



There are two theories about the morphology of the flower. 

 Some regard the male as one flower of many stamens ; others, 

 however, consider each stamen as a separate flower, hence the 

 difference in the terms flower, catkin, and cone, apjjlied to the 

 male inflorescence. Similarly the female cone may be regarded 

 as a single flower composed of many bracts and scales, or each 

 bract with its seed scale may be treated as a distinct flower. 



The number of ovules to each fertile scale varies considerably 

 in different genera. Sometimes it is solitary, as in Taxus ; in Pinus 

 there are two seeds to each scale, while in some species of Cupressus 

 they are numerous. 



Further details of external morphology will be found under 

 the descriptions of the various genera. 



Wood. 



The wood is distinguished from that of other flowering plants in 

 the absence of vessels, and is composed of tracheids or elongated 

 spindle-shaped cells with closed ends which are dovetailed between 

 one another. They have woody walls marked with bordered 

 pits, which are a characteristic feature of coniferous woods. The 

 medullary rays traversing the wood are usually only one cell 

 thick and rarely visible without a lens. In some genera (notably 

 Pinus) resin ducts are conspicuous as small dots on the transverse 

 surface of the wood, whilst in certain other genera (Abies) 



