INFLORESCENCE. 35 



surface chiefly, or on both, and where the leaves are three-sided as in 

 many species of Pinus, they occur chiefly on the two flat sides. The 

 first-named position is the most common ; it predominates throughout 

 the Taxacese, Abies, Tsuga, the flat-leaved species of Picea, Larix, etc. 

 The species in which the stomata occur chiefly on the upper surface are 

 mostly included in the Cupressinese, that surface being the only exposed 

 one in nearly all the genera; even those species of Juniperus with 

 acicular free or partially free leaves form 110 exception. Instances in 



which stomata are found on both sur- 

 faces occur in Cryptomeria, Sequoia 

 (Wellingtonia), Athrotaxis and a few 

 others. The arrangement of the stomata 

 is for the most part quite formal ; in 

 Pinus they are disposed in longitudinal 

 roAVS, the position being indicated by 

 grey lines which add so greatly to the 

 beauty of the foliage of these trees, 

 especially those with five leaves in 

 each bundle ; in Abies, Tsuga, the 

 flat-leaved species of Picea, Larix, also 



T "TaS. i0n fleaf0f in some of the Taxace^ (Cephalotaxus, 



Prumnopitys, etc.) they are disposed in 



a longitudinal band on each side of the midrib on the under side 

 of the leaf, forming the characteristic white bands of these species, and 

 frequently, for descriptive purposes, called the stomatiferous bands. 

 The silvery band on the upper surface of the acicular leaves of 

 Juniperus is also a stomatiferous band. In Arancaria the stomata are 

 arranged in bands composed of few or many rows ; according to 

 Bertrand there are as many as seventy rows on each side of a leaf of 

 A. imbrif'ata. Whilst the formal arrangement prevails throughout the 

 majority of the species, there are instances in which the stomata are 

 irregularly disposed or confined to certain localities on one or both 

 surfaces of the leaf. 



INFLOBESCENCE. 



THE flowers of Taxads and Conifers are always unisexual, and the 

 plants therefore are either monoecious when flowers of both sexes 

 are borne 011 the same individual, or dioecious when the staminiferous 

 (male) and ovuliferous (female) flowers are borne on different 

 individuals. In the TAXACE.E, dioecity is probably absolute in Ginkgo 

 and in two or three of the Australian genera; it is relatively so in 

 Taxus, Cephalotaxus and Torreya, in which flowers of both sexes have 

 been observed on the same tree. This is not uncommon in the 

 Yew, and when it occurs the two kinds are on different branches. 

 En the CONIFERS the flowers are monoecious throughout except 

 in Fitzroya, Araucaria and Juniperus, but in the last named genus 

 the two sexes are often found on different branches of the same 

 tree ; and in Araucaria, at least in A. imbricata, dicecity is not 

 absolute. The Australian genera Callitris and Actinostrobus are also 

 probably dioecious. 



